Immersion in water during labour and birth

Elizabeth R Cluett; Ethel Burns; Anna Cuthbert

doi:10.1002/14651858.CD000111.pub4

. 2018 May 16;2018(5):CD000111. doi: 10.1002/14651858.CD000111.pub4

Immersion in water during labour and birth

Elizabeth R Cluett ^1,^✉, Ethel Burns ², Anna Cuthbert ³

Editor: Cochrane Pregnancy and Childbirth Group

PMCID: PMC6494420 PMID: 29768662

Abstract

Background

Water immersion during labour and birth is increasingly popular and is becoming widely accepted across many countries, and particularly in midwifery‐led care settings. However, there are concerns around neonatal water inhalation, increased requirement for admission to neonatal intensive care unit (NICU), maternal and/or neonatal infection, and obstetric anal sphincter injuries (OASIS). This is an update of a review last published in 2011.

Objectives

To assess the effects of water immersion during labour and/or birth (first, second and third stage of labour) on women and their infants.

Search methods

We searched Cochrane Pregnancy and Childbirth’s Trials Register, ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) (18 July 2017), and reference lists of retrieved trials.

Selection criteria

We included randomised controlled trials (RCTs) comparing water immersion with no immersion, or other non‐pharmacological forms of pain management during labour and/or birth in healthy low‐risk women at term gestation with a singleton fetus. Quasi‐RCTs and cluster‐RCTs were eligible for inclusion but none were identified. Cross‐over trials were not eligible for inclusion.

Data collection and analysis

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. Two review authors assessed the quality of the evidence using the GRADE approach.

Main results

This review includes 15 trials conducted between 1990 and 2015 (3663 women): eight involved water immersion during the first stage of labour; two during the second stage only; four during the first and second stages of labour, and one comparing early versus late immersion during the first stage of labour. No trials evaluated different baths/pools, or third‐stage labour management. All trials were undertaken in a hospital labour ward setting, with a varying degree of medical intervention considered as routine practice. No study was carried out in a midwifery‐led care setting. Most trial authors did not specify the parity of women. Trials were subject to varying degrees of bias: the intervention could not be blinded and there was a lack of information about randomisation, and whether analyses were undertaken by intention‐to‐treat.

Immersion in water versus no immersion (first stage of labour)

There is probably little or no difference in spontaneous vaginal birth between immersion and no immersion (83% versus 82%; risk ratio (RR) 1.01, 95% confidence interval (CI) 0.97 to 1.04; 6 trials; 2559 women; moderate‐quality evidence); instrumental vaginal birth (12% versus 14%; RR 0.86, 95% CI 0.70 to 1.05; 6 trials; 2559 women; low‐quality evidence); and caesarean section (5% versus 4%; RR 1.27, 95% CI 0.91 to 1.79; 7 trials; 2652 women; low‐quality evidence). There is insufficient evidence to determine the effect of immersion on estimated blood loss (mean difference (MD) ‐14.33 mL, 95% CI ‐63.03 to 34.37; 2 trials; 153 women; very low‐quality evidence) and third‐ or fourth‐degree tears (3% versus 3%; RR 1.36, 95% CI 0.85 to 2.18; 4 trials; 2341 women; moderate‐quality evidence). There was a small reduction in the risk of using regional analgesia for women allocated to water immersion from 43% to 39% (RR 0.91, 95% CI 0.83 to 0.99; 5 trials; 2439 women; moderate‐quality evidence). Perinatal deaths were not reported, and there is insufficient evidence to determine the impact on neonatal intensive care unit (NICU) admissions (6% versus 6%; average RR 1.30, 95% CI 0.42 to 3.97; 2 trials; 1511 infants; I² = 36%; low‐quality evidence), or on neonatal infection rates (1% versus 1%; RR 2.00, 95% CI 0.50 to 7.94; 5 trials; 1295 infants; very low‐quality evidence).

Immersion in water versus no immersion (second stage of labour)

There were no clear differences between groups for spontaneous vaginal birth (98% versus 97%; RR 1.02, 95% CI 0.96 to 1.08; 120 women; 1 trial; low‐quality evidence); instrumental vaginal birth (2% versus 2%; RR 1.00, 95% CI 0.06 to 15.62; 1 trial; 120 women; very low‐quality evidence); caesarean section (0% versus 2%; RR 0.33, 95% CI 0.01 to 8.02; 1 trial; 120 women; very low‐quality evidence), and NICU admissions (8% versus 11%; RR 0.78, 95% CI 0.38 to 1.59; 2 trials; 291 women; very low‐quality evidence). Use of regional analgesia was not relevant to the second stage of labour. Third‐ or fourth‐degree tears, and estimated blood loss were not reported in either trial. No trial reported neonatal infection but did report neonatal temperature less than 36.2°C at birth (9% versus 9%; RR 0.98, 95% CI 0.30 to 3.20; 1 trial; 109 infants; very low‐quality evidence), greater than 37.5°C at birth (15% versus 6%; RR 2.62, 95% CI 0.73 to 9.35; 1 trial; 109 infants; very low‐quality evidence), and fever reported in first week (2% versus 5%; RR 0.53, 95% CI 0.10 to 2.82; 1 trial; 171 infants; very low‐quality evidence), with no clear effect between groups being observed. One perinatal death occurred in the immersion group in one trial (RR 3.00, 95% CI 0.12 to 72.20; 1 trial; 120 infants; very low‐quality evidence). The infant was born to a mother with HIV and the cause of death was deemed to be intrauterine infection.

There is no evidence of increased adverse effects to the baby or woman from either the first or second stage of labour.

Only one trial (200 women) compared early and late entry into the water and there were insufficient data to show any clear differences.

Authors' conclusions

In healthy women at low risk of complications there is moderate to low‐quality evidence that water immersion during the first stage of labour probably has little effect on mode of birth or perineal trauma, but may reduce the use of regional analgesia. The evidence for immersion during the second stage of labour is limited and does not show clear differences on maternal or neonatal outcomes intensive care. There is no evidence of increased adverse effects to the fetus/neonate or woman from labouring or giving birth in water. Available evidence is limited by clinical variability and heterogeneity across trials, and no trial has been conducted in a midwifery‐led setting.

Plain language summary

Immersion in water in labour and birth

What is the issue?

To assess the effects of water immersion (waterbirth) during labour and/or birth (first, second and third stage of labour) on women and their infants.

Why is this important?

Many women choose to labour and give birth in water (water immersion) and this practice is becoming more popular in many countries, particularly in midwifery‐led units. Therefore, it is important to understand more about the benefits of water immersion in labour and birth for women and their newborns, along with any risks.

It is important to examine whether immersion in water during the first and/or the second stage of labour has the potential to maximise women's ability to manage labour pain, and to have a normal birth without increasing the risk of an adverse (harmful) event. Adverse events might be an increased risk of infection for women and/or their newborn; an increased likelihood of a serious tear to the perineum (the area between anus and vagina), and it may make estimating blood loss more difficult in the event of a haemorrhage. In assessing the benefits, we consider well‐being to cover both physical and psychological health.

What evidence did we find?

We included 15 trials (3663 women). All the trials compared immersion in water with no immersion in water: eight during the first stage of labour, two during the second stage of labour (waterbirth) only, four during the first and second stages of labour, and one early versus late immersion during the first stage of labour. The evidence was of moderate to very low quality. No trial compared immersion in water with other forms of pain management.

Water immersion during the first stage of labour probably results in fewer women having an epidural, but probably makes little or no difference to the number of women who have a normal vaginal birth, instrumental birth, caesarean section or a serious perineal tear. We are uncertain about the effect on the amount of blood loss after birth because the quality of the evidence was very low. Labouring in water also may make little or no difference to babies being admitted to neonatal intensive care unit (NICU) or developing infections. Stillbirths and baby deaths were not reported.

Two trials compared water immersion during the second stage (birth) with no immersion. We found that immersion may make little or no difference in numbers of women who have a normal vaginal birth. It is uncertain whether immersion makes any difference to instrumental vaginal births, caesarean sections, numbers of babies admitted to NICU, babies' temperatures at birth and fever in babies during the first week, because the quality of the evidence was found to be very low for all of these outcomes. Epidurals were not relevant to this stage of labour. Serious perineal tears and blood loss after birth were not reported in either trial.

Only one trial (200 women) compared women who got into the water early and late in their labour but there was not enough information to show any clear differences between the groups.

What does this mean?

Labouring in water may reduce the number of women having an epidural. Giving birth in water did not appear to affect mode of birth, or the number of women having a serious perineal tear. This review found no evidence that labouring in water increases the risk of an adverse outcome for women or their newborns. The trials varied in quality and further research is needed particularly for waterbirth and its use in birth settings outside hospital labour wards before we can be more certain of these effects. Research is also needed about women’s and caregivers experiences of labour and birth in water.

Summary of findings

Background

This review is one in a series of Cochrane Reviews examining pain management in labour. An earlier version of this review contributed to an overview of systematic reviews of pain management for women in labour (Jones 2012) and shared a generic protocol (Jones 2011).

A history of water immersion

The use of water immersion as a therapeutic medium is not new. Its exact origins are unknown, but there is evidence of immersion in water being used as a treatment for physical and psychological ill health by the Chinese, Egyptians, Japanese and Assyrians, as well as Greeks and Romans (Reid Campion 1990; Reid‐Campion 1997). Warm water immersion during labour, including birth, used for relaxation and pain relief, has a long history in lay and clinical care (Garland 2000). Igor Tjarkovsky, a Russian boat builder, stimulated the foundation of a movement to promote waterbirth in Soviet Russia in the 1970s. He became convinced of the benefits of water immersion as a means of maximising physiological potential. Michel Odent subsequently popularised water immersion in other European countries (Odent 1983). Although considered a fad by some, the use of water during labour and birth appeals to both women and their carers, particularly those striving for a woman‐centred, intervention‐free, 'normal' experience. In 1995, the first international waterbirth conference was held in London, followed by many subsequent study events and international conferences.

In 1993, the use of water immersion during labour gained acceptance as a care option in the UK. A key report into maternity service provision, the Changing Childbirth publication recommended that a pool facility should be an option available to women in all UK maternity units (Department of Health 1993). Professional recognition of the use of water during labour and birth followed in 1994 when both the Royal College of Midwives and the United Kingdom Central Council for Nursing, Midwifery and Health Visiting published position statements, which incorporated water immersion during labour into the role of the midwife (RCM 1994; UKCC 1994). The use of water during labour/birth is now integrated in the UK Nursing and Midwifery Council's Midwifery Rules and Standards (NMC 2012), and clinical guidelines (NICE 2014).

Evidence indicates that labouring and giving birth in water is gaining in popularity internationally (Dahlen 2013; Geissbuehler 2004; Henderson 2014; New Zealand College of Midwives 2017), and is emerging as a means of facilitating women to have a greater sense of control and comfort during childbirth (Maude 2007; Richmond 2003). The buoyancy that labouring in water offers can reduce women’s pain perception (Benfield 2010). The calmer and more in control a woman feels during labour reduces her likelihood of requiring interventions such as labour augmentation, and operative birth.

There is an association between birthing pool use during labour, particularly in midwifery‐led settings (alongside/free‐standing midwifery units) and fewer interventions during labour and birth for healthy pregnant women (Burns 2012). This is important in the context of increasing global concern about escalating caesarean section rates without evidence of a concomitant improvement in perinatal mortality (Gibbons 2010; Johanson 2002; McLachlan 2012; National Childbirth Trust 2011; Sufang 2007), and a national drive in the UK to promote midwifery settings as the optimal place of birth for healthy pregnant women (NICE 2014; RCOG 2011). A seminal national prospective study in the UK also found that healthy women who laboured and gave birth in midwifery settings experienced fewer interventions and fewer complications compared with similar women who planned to give birth in a hospital labour ward (Birthplace Collaboration 2011). Birthing pools are most commonly used in midwifery‐led units. A birthing pool therefore offers midwives an opportunity to develop the skills required to provide woman‐centred care, form a therapeutic rapport with women, facilitate their freedom and participation in decision making, and support them in having choice and control over their care (NMC 2012). Importantly, it may also facilitate them to increase the incidence of normal birth as defined in Normal Birth Consensus Statement (Burns 2012; Maternity Care Working Party 2007).

Description of the condition

This review is about care and management of women during labour and birth. It is one in a series of Cochrane reviews examining pain management in labour.

Labour is understood to be as defined by the woman or clinicians at the time, and includes regular painful uterine contractions, leading to full cervical dilation, expulsion of the fetus, and the placenta and membranes.

Description of the intervention

Throughout this review, 'water immersion' refers to the immersion in water by a pregnant woman during any stage of labour (first, second, third) where the woman's abdomen is completely submerged. 'Waterbirth' refers to where the neonate is born under the water. This implies the use of a receptacle that may be called a pool, tub or bath, and which is larger than a normal domestic bath. The period of immersion by the woman may be for one or more stages of labour, and for any duration. Labour is understood to be as defined by the woman or clinicians at the time, and includes regular painful uterine contractions, leading to full cervical dilation, expulsion of the fetus, and the placenta and membranes.

Water immersion during the first and second stage of labour

Prospective observational studies have shown an association between labouring in water and a greater likelihood of having a spontaneous vaginal birth, especially among nulliparous women (Burns 2012; Geissbuehler 2004; Henderson 2014; Lukasse 2014). Research involving women who laboured in water in midwifery‐led units reported a low intrapartum transfer incidence, particularly from the community setting (Bovbjerg 2016, Burns 2012), and lower when compared with women who did not use water immersion (Lukasse 2014).

The UK is promoting water immersion during labour and waterbirth as a means of empowering women, and is consistent with the initiative to normalise birth and reduce inappropriate use of interventions (RCM 2016), which has been supported in evidence form cohort studies (Bovbjerg 2016; Burns 2012; Lukasse 2014). All maternity units are recommended to have at least one birthing pool, and there is a policy drive to encourage healthy pregnant women to give birth in midwifery‐led settings (for example, alongside midwifery units situated inside the hospital, freestanding midwifery‐led units located in the community), and home birth (NHS 2014; RCOG 2011), consistent with the view that non‐medical settings improve outcomes (Hodnett 2012). It is estimated that at least 60% of pregnant women in the UK are healthy and experience a straightforward pregnancy (Birthplace Collaboration 2011; RCOG 2011), and are therefore eligible to give birth in midwifery‐led settings where a birthing pool use is an established, core care option.

'Normal birth' is a composite outcome defined as a spontaneous labour onset, no epidural, spontaneous vaginal birth with no episiotomy (Maternity Care Working Party 2007), has been identified as a care quality marker (Dodwell 2010). The largest prospective national cohort study showed that this outcome was more likely to occur in a midwifery‐led setting (Birthplace Collaboration 2011); a finding echoed among women who used a birthing pool during labour and planned to give birth in the community (Burns 2012).

It has been suggested that waterbirth may reduce the uptake of pharmacological pain relief and increase the likelihood of an intact perineum (Burke 1995; Burns 2012; Garland 2010; Geissbuehler 2004; Henderson 2014; Otigbah 2000). There may also be increased maternal satisfaction with the birth experience (Hall 1998; Maude 2007). Waterbirth may facilitate healthy pregnant women to have a normal birth, and particularly nulliparous women who plan to give birth in the community setting (Burns 2012). Retrospective analysis suggested that waterbirth might predispose women to a greater risk of sustaining obstetric anal sphincter injury (OASIS) (Cortes 2011). However, a prospective study (N = 2745 women) that investigated risk factors for perineal trauma found no link to indicate that labouring in water might predispose women to have a perineal tear (Smith 2013), and two prospective studies found no evidence identifying waterbirth as a risk factor for OASIS (Burns 2012; Henderson 2014). Although historically concerns were raised that waterbirth may present a risk factor for maternal infection (Hawkins 1995; Rawal 1994; Rosevear 1993), there is no current evidence for this.

Concerns raised for the neonate born under water are fourfold. First, concerns have been raised by several authors (Deans 1995; Johnson 1996; Rosser 1994), for fetal (and hence neonatal) well‐being if a woman becomes pyrexial due to immersion in water warmer than her own natural core temperature. Ensuring pool temperature remains below maternal temperature is often recommended to prevent this. Secondly, it has been suggested that fetal/neonatal infection may occur due to cross‐contamination from the water and pool, and from the woman (Hawkins 1995; Rawal 1994). However, several trials, comparative studies, cohort studies, and audits report no increased risk of infection for the fetus/neonate (Alderdice 1995; Anderson 1996; Eriksson 1997; Otigbah 2000; Robertson 1998; Rush 1996; Zanetti‐Daellenbach 2007). As with all maternity provision, it is incumbent upon practitioners to ensure they have appropriate cleaning protocols for labour and birthing pools, and employ universal precautions. Thirdly, there have been case reports of transient tachypnoea of the newborn (TTN) following waterbirth (Kassim 2005; Mammas 2009; Nguyen 2002; Schroeter 2004; Sotiridou 2012). There is some debate among paediatricians, but no evidence beyond case reports about whether waterbirth predisposes a newborn to a greater risk of TTN than land birth (Carpenter 2012; Pinette 2004). However, neither the largest observational studies for waterbirth (Bovbjerg 2016; Burns 2012; Geissbuehler 2004), the randomised controlled trials that involved waterbirths (Chaichian 2009; Gayiti 2015; Ghasemi 2013; Nikodem 1999; Torkamani 2010; Woodward 2004), or a systematic review (Taylor 2016) have reported cases of TTN. Finally, concerns have been raised about the dangers of umbilical cords at water births (Cro 2002; Gilbert 1999). Cords also snap in land births; there are however, no data for this. Cord snaps associated with waterbirth may be related to undue traction exerted on the cord as the baby is lifted out of the water (Burns 2012).

Third stage of labour

Limited data are available on the third stage of labour management during water immersion. Two prospective cohort studies, one involving a UK sample of women (Burns 2012), and the second, an Italian sample (Henderson 2014), reported on third‐stage management and the incidence of postpartum haemorrhage (PPH) for women who used water immersion during labour and for women who had a waterbirth. Both studies found a low incidence of PPH, and a higher use of physiological third stage (no oxytocic drug injection prior to birth of the placenta) among women who had a waterbirth.

How the intervention might work

The positive physiological effects of hydrotherapy such as buoyancy, hydrostatic pressure, and associated thermal changes, are relevant to women labouring in water, where labour is defined as including the first, second (birth) and third stages. The buoyancy of water enables a woman to move more easily than on land (Edlich 1987). This can facilitate the neuro‐hormonal interactions of labour, alleviating pain, and potentially optimising the progress of labour (Benfield 2010; Ginesi 1998a; Ginesi 1998b). Water immersion may be associated with improved uterine perfusion, less painful contractions, a shorter labour with fewer interventions (Aird 1997; Garland 2000; Geissbuehler 2004; Henderson 2014; Moneta 2001; Otigbah 2000; Thoeni 2005; Zanetti‐Daellenbach 2007). In addition, the ease of mobility that water immersion offers women may optimise fetal position by encouraging flexion (Ohlsson 2001). Where water immersion reduces the use of any pharmacological analgesia, either completely or partly, then the fetus/neonate benefits from not being exposed to the side effects of such drugs.

Hydrotherapy has marked physiological effects on the cardiovascular system (Cefalo 1978). Shoulder‐deep warm water immersion has been shown to reduce blood pressure due to vasodilatation of the peripheral vessels and redistribution of blood flow. It is suggested that water immersion during labour increases maternal satisfaction and sense of control (Hall 1998; Richmond 2003). A woman who feels in control during childbirth experiences greater emotional well‐being postnatally (Green 1998; Green 2007; Maude 2007; Meyer 2012).

Why it is important to do this review

Evidence is growing on the benefits of water immersion during labour for the woman and fetus; and of the potential benefits during waterbirth. However, some controversy remains, particularly around the risk of severe perineal trauma and neonatal well‐being. Importantly, most of the evidence on the use of water immersion during labour and waterbirth is based on observational studies (Burns 2012; Garland 2000; Garland 2006; Geissbuehler 2000; Geissbuehler 2004; Henderson 2014; Lukasse 2014; Ohlsson 2001; Thoeni 2005). Understanding the findings of the randomised controlled trials to date may help to elicit causal relationships and/or greater confidence in results to date. This is particularly important given the current drive to normalise birth and reduce unnecessary intervention during labour and birth. This is an update of a review last published in 2011 (Cluett 2009).

Objectives

To assess the effects of water immersion during labour and/or birth (first, second and third stage of labour) on women and their infants.

Methods

Criteria for considering studies for this review

Types of studies

We included randomised controlled trials (RCTs) that assessed the use of water immersion as a form of pain relief. Quasi‐randomised and cluster‐randomised trials were eligible for inclusion but none were identified. Cross‐over trials were not eligible for inclusion because irrespective of maternal parity, the duration of the first and second stage of labour cannot be predicted with a high level of accuracy between women; a factor which would prevent being able to guarantee equitable cross‐over and therefore data precision.

If trials had included randomised and non‐randomised women and if the randomised data were presented separately, we planned to report this. We have included published, unpublished and ongoing studies with reported data. We included trial reports in abstract form.

Types of participants

Nulliparous or multiparous women in labour at term gestation (as defined by trial authors), with a singleton pregnancy, where the woman and her fetus were healthy, and at low risk of complications.

Types of interventions

The previous version of this review (Cluett 2009) contributed to an overview of systematic reviews of interventions for pain management in labour (Jones 2012), and shared a generic protocol (Jones 2011). To avoid duplication, the different methods of pain management were listed in a specific order, from one to 15. Individual reviews focusing on particular interventions included comparisons with only the intervention above it on the list. The list is as follows.

Placebo/no treatment
Hypnosis (Madden 2016)
Biofeedback (Barragán 2011)
Intracutaneous or subcutaneous sterile water injection (Derry 2012)
Immersion in water (this review)
Aromatherapy (Smith 2011a)
Relaxation techniques (yoga, music, audio) (Smith 2011b)
Acupuncture or acupressure (Smith 2011c)
Manual methods (massage, reflexology) (Smith 2012)
Transcutaneous electrical nerve stimulation (TENS) (Dowswell 2009)
Inhaled analgesia (Klomp 2012)
Opioids (Ullman 2010)
Non‐opioid drugs (Othman 2011)
Local anaesthetic nerve blocks (Novikova 2011)
Epidural (including combined spinal epidural) (Anim‐Somuah 2005; Simmons 2007)

Accordingly, this review includes comparisons of any kind of bath/tub/pool that enabled immersion during any stage of labour, regardless of care setting, compared with: 1. no treatment (no immersion); 2. hypnosis; 3. biofeedback; 4. intracutaneous or subcutaneous sterile water injection; and 5. immersion during a different stage of labour.

However, only trials of immersion versus no immersion have been identified to date.

Types of outcome measures

We chose primary outcomes that we thought would be the most clinically valuable in assessing safety and effectiveness for the woman, fetus/neonate and caregivers. In addition, we identified outcomes that were considered to be of interest from the perspective of the woman and her baby, primary caregivers and related service providers. We also included outcomes to be consistent with the overview of systematic reviews of interventions for pain management in labour (Jones 2012).

We then selected the most pertinent maternal and fetal/neonatal outcomes for water immersion as primary outcomes. These (list below) are analysed within the comparison groups:

immersion in water versus no immersion during the first stage of labour;
immersion in water versus no immersion during the second stage of labour;
immersion in water versus no immersion during any stage of labour;
immersion in water versus no immersion during the third stage of labour (no trial reported this comparison);
early (cervical dilation less than 5 cm) with late (cervical dilation more than 5 cm) immersion.

Primary outcomes

Maternal

Mode of birth (spontaneous vaginal birth, instrumental vaginal birth and caesarean section)
Use of analgesia (regional) during any stage of labour
Perineal trauma (third‐degree or fourth‐degree tear)

Fetal/Neonatal

Perinatal death (still birth, neonatal death)
Admission to neonatal intensive care unit
Neonatal infection, including markers of infection such as pyrexia and raised white cell count

Secondary outcomes

Maternal

Mortality
Labour
1. Estimated blood loss
2. Postpartum haemorrhage (> 500 mL)
3. Use of analgesia (general anaesthesia, pharmacological analgesia, or other) during any stage of labour
4. Infection during labour/postnatal period
5. Augmentation of labour (artificial rupture of membranes and/or oxytocin administration)
6. Use of non‐pharmacological analgesia
7. Duration of labour (first, second and third stage)
8. Perineal trauma (none ‐intact, first‐degree tear, second‐degree tear, episiotomy)
9. Pain experience/intensity as presented by authors
10. Temperature (degrees Centigrade) (first and second stage)
11. Pulse and blood pressure (first, second and third stage)
12. Maternal self‐esteem
13. Preference for care in subsequent labour
14. Satisfaction with childbirth experience (as defined by trialists)
15. Satisfaction with pain relief (as defined by trialists)
16. Sense of control in labour (as defined by trialists)
17. Effect (negative) on mother/baby interaction

Long‐term outcomes
1. Postpartum depression
2. Post‐traumatic stress disorder

Fetal/Neonatal outcomes

Abnormal heart rate pattern
Meconium liquor
Apgar score less than seven at five minutes (or as presented by authors)
Cord pH immediately after birth (arterial and or venous cord blood)
Respiratory support (oxygen/ventilation required)
Lung hypoplasia
Neurological pathology, e.g. seizures, cerebral palsy
Snapped cord
Birth injury
Breastfeeding (at specified time points)
Poor infant outcomes at long‐term follow‐up (as defined by trialists)

Other

Cost as defined by trialists

Caregiver outcomes

Satisfaction
Injuries (any reported physical injury attributed to care of women in water)

Search methods for identification of studies

The following methods section of this review is based on a standard template used by Cochrane Pregnancy and Childbirth.

Electronic searches

For this update, we searched Cochrane Pregnancy and Childbirth’s Trials Register by contacting their Information Specialist (18 July 2017).

The Register is a database containing over 24,000 reports of controlled trials in the field of pregnancy and childbirth. It represents over 30 years of searching. For full current search methods used to populate Pregnancy and Childbirth’s Trials Register including the detailed search strategies for CENTRAL, MEDLINE, Embase and CINAHL; the list of handsearched journals and conference proceedings, and the list of journals reviewed via the current awareness service, please follow this link to the editorial information about the Cochrane Pregnancy and Childbirth in the Cochrane Library and select the ‘Specialized Register ’ section from the options on the left side of the screen.

Briefly, Cochrane Pregnancy and Childbirth’s Trials Register is maintained by their Information Specialist and contains trials identified from:

monthly searches of the Cochrane Central Register of Controlled Trials (CENTRAL);
weekly searches of MEDLINE (Ovid);
weekly searches of Embase (Ovid);
monthly searches of CINAHL (EBSCO);
handsearches of 30 journals and the proceedings of major conferences;
weekly current awareness alerts for a further 44 journals plus monthly BioMed Central email alerts.

Search results are screened by two people and the full text of all relevant trial reports identified through the searching activities described above is reviewed. Based on the intervention described, each trial report is assigned a number that corresponds to a specific Pregnancy and Childbirth review topic (or topics), and is then added to the Register. The Information Specialist searches the Register for each review using this topic number rather than keywords. This results in a more specific search set that has been fully accounted for in the relevant review sections (Included studies; Excluded studies; Ongoing studies).

In addition, we searched ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) for unpublished, planned and ongoing trial reports (18 July 2017) using the terms given in Appendix 1

Searching other resources

We searched the reference lists of retrieved studies.

We did not apply any language or date restrictions.

Data collection and analysis

For methods used in the previous version of this review, seeCluett 2009.

For this update, we used the following methods for assessing the 14 reports that were identified as a result of the updated search.

The following methods section of this review is based on a standard template used by the Cochrane Pregnancy and Childbirth Review Group.

Selection of studies

Two review authors independently assessed for inclusion all the potential studies identified as a result of the search strategy. We resolved any disagreement through discussion.

Data extraction and management

We designed a form to extract data. For eligible studies, two review authors extracted the data using the agreed form. We resolved discrepancies through discussion. Data were entered into Review Manager software (RevMan 2014) by one review author (EC) and checked for accuracy by a second review author (EB).

When information regarding any of the above was unclear, we endeavoured to contact authors of the original reports to provide further details.

We decided to present the data by stage of labour, first, second and third stage. Where a trial involved immersion in labour during first and second stages, we decided to present data in both subgroups. This was because the key outcomes of interest to practitioners and women are presented in clinical practice as ultimate birth outcome regardless of management strategies adopted.

Assessment of risk of bias in included studies

Two review authors independently assessed risk of bias for each study using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). Any disagreement was resolved by discussion.

(1) Random sequence generation (checking for possible selection bias)

We described for each included study the method used to generate the allocation sequence in sufficient detail to allow an assessment of whether it should produce comparable groups.

We assessed the method as:

low risk of bias (any truly random process, e.g. random number table; computer random number generator);
high risk of bias (any non‐random process, e.g. odd or even date of birth; hospital or clinic record number); or;
unclear risk of bias.

(2) Allocation concealment (checking for possible selection bias)

We described for each included study the method used to conceal allocation to interventions prior to assignment and assessed whether intervention allocation could have been foreseen in advance of, or during recruitment, or changed after assignment.

We assessed the methods as:

low risk of bias (e.g. telephone or central randomisation; consecutively numbered sealed opaque envelopes);
high risk of bias (open random allocation; unsealed or non‐opaque envelopes, alternation; date of birth);
unclear risk of bias.

(3.1) Blinding of participants and personnel (checking for possible performance bias)

Due to the nature of the intervention women, carers' and researchers cannot be blind to group allocation after randomisation and so all studies are considered to be at high risk of bias for this domain.

(3.2) Blinding of outcome assessment (checking for possible detection bias)

No study included in this review reported any blinding of outcome assessment. However most outcomes were recorded by the professional providing data for example method of birth, duration of labour which are routine outcomes, so are unlikely to be biased.

As a consequence we have assessed methods used to blind outcome assessment as:

unclear risk of bias.

(4) Incomplete outcome data (checking for possible attrition bias due to the amount, nature and handling of incomplete outcome data)

We described for each included study, and for each outcome or class of outcomes, the completeness of data including attrition and exclusions from the analysis. We stated whether attrition and exclusions were reported and the numbers included in the analysis at each stage (compared with the total randomised participants), reasons for attrition or exclusion where reported, and whether missing data were balanced across groups or were related to outcomes.

We assessed methods as:

low risk of bias (e.g. no missing outcome data; missing outcome data balanced across groups, less than 20% loss);
high risk of bias (e.g. numbers or reasons for missing data imbalanced across groups; ‘as treated” analysis done with substantial departure of intervention received from that assigned at randomisation);
unclear risk of bias.

(5) Selective reporting (checking for reporting bias)

We described for each included study how we investigated the possibility of selective outcome reporting bias and what we found.

We assessed the methods as:

low risk of bias (where it is clear that all of the study’s pre‐specified outcomes and all expected outcomes of interest to the review have been reported);
high risk of bias (where not all the study’s pre‐specified outcomes have been reported; one or more reported primary outcomes were not pre‐specified; outcomes of interest are reported incompletely and so cannot be used; study fails to include results of a key outcome that would have been expected to have been reported);
unclear risk of bias.

(6) Other bias (checking for bias due to problems not covered by (1) to (5) above)

We described for each included study any important concerns we had about other possible sources of bias.

We assessed whether each study was free of other problems that could put it at risk of bias:

low risk of other bias;
high risk of other bias;
unclear whether there is risk of other bias.

(7) Overall risk of bias

We made explicit judgements about whether studies were at high risk of bias, according to the criteria given in the Handbook (Higgins 2011). With reference to (1) to (6) above, we assessed the likely magnitude and direction of the bias and considered the likely impact on the findings.

Assessment of the quality of the evidence using the GRADE approach

For this update, we assessed the quality of the evidence using the GRADE approach as outlined in the GRADE handbook in order to assess the quality of the body of evidence relating to the following outcomes.

Mode of birth (spontaneous vaginal birth, instrumental vaginal birth, and caesarean section)
Use of analgesia (regional) during any stage of labour
Perineal trauma (third‐ or fourth‐degree tear)
Perinatal mortality
Admission to special care baby unit/neonatal intensive care unit
Neonatal infection, including markers of infection such as pyrexia and raised white cell count
Estimated blood loss

We assessed the evidence for the main comparisons: immersion in water versus no immersion during first stage of labour; and immersion in water versus no immersion during second stage of labour.

We used the GRADEpro Guideline Development Tool to import data from Review Manager 5.3 (RevMan 2014) in order to create ’Summary of findings’ tables. A summary of the intervention effect and a measure of quality for each of the above outcomes was produced using the GRADE approach. The GRADE approach uses five considerations (study limitations, consistency of effect, imprecision, indirectness and publication bias) to assess the quality of the body of evidence for each outcome. The evidence can be downgraded from 'high quality' by one level for serious (or by two levels for very serious) limitations, depending on assessments for risk of bias, indirectness of evidence, serious inconsistency, imprecision of effect estimates or potential publication bias.

Measures of treatment effect

Dichotomous data

For dichotomous data, we presented results as summary risk ratio with 95% confidence intervals.

Continuous data

We used the mean difference if outcomes were measured in the same way between trials. We planned to use the standardised mean difference to combine trials that measured the same outcome, but used different methods.

Unit of analysis issues

Cluster‐randomised trials

We planned to include cluster‐randomised trials, however none were identified. In future updates, if cluster‐randomised trials are included, we will include cluster‐randomised trials in the analyses along with individually‐randomised trials. We will adjust their sample size using the methods described in Section 16.3.4 of the Handbook (Higgins 2011) using an estimate of the intracluster correlation co‐efficient (ICC) derived from the trial (if possible), from a similar trial or from a study of a similar population. If we use ICCs from other sources, we will report this and conduct sensitivity analyses to investigate the effect of variation in the ICC. If we identify both cluster‐randomised trials and individually‐randomised trials, we plan to synthesise the relevant information. We will consider it reasonable to combine the results from both if there is little heterogeneity between the study designs and the interaction between the effect of intervention and the choice of randomisation unit is considered to be unlikely.

We will also acknowledge heterogeneity in the randomisation unit and perform a sensitivity analysis to investigate the effects of the randomisation unit.

Cross‐over trials would not be a feasible or valid design for this topic and were therefore not eligible for inclusion. No other unit of analysis issues were identified.

Dealing with missing data

We analysed data on all participants with available data in the group to which they were allocated, regardless of whether or not they received the allocated intervention, and irrespective of whether they used additional interventions. If, in the original reports, participants were not analysed in the group to which they were randomised, and there was sufficient information in the trial report, we have attempted to restore them to the correct group.

For included studies we noted levels of attrition.

Where data were not reported for some outcomes or groups, we attempted to contact the study authors.

Assessment of heterogeneity

We assessed statistical heterogeneity in each meta‐analysis using the Tau², I² and Chi² statistics. We regarded heterogeneity as substantial if an I² was greater than 30% and either a Tau² was greater than zero, or there was a low P value (less than 0.10) in the Chi² test for heterogeneity. Had we identified substantial heterogeneity (above 30%), we planned to explore it by pre‐specified subgroup analysis.

Assessment of reporting biases

If there were 10 or more studies in any meta‐analysis, we planned to investigate reporting biases (such as publication bias) using funnel plots. There was a single meta‐analysis with 10 studies. We assessed funnel plot asymmetry visually in this single meta‐analysis.

Data synthesis

We carried out statistical analysis using the Review Manager software (RevMan 2014). We used fixed‐effect meta‐analysis for combining data where it was reasonable to assume that studies were estimating the same underlying treatment effect: i.e. where trials were examining the same intervention, and the trials’ populations and methods were judged sufficiently similar.

If there was clinical heterogeneity sufficient to expect that the underlying treatment effects differed between trials, or if substantial statistical heterogeneity was detected, we used random‐effects meta‐analysis to produce an overall summary, if an average treatment effect across trials was considered clinically meaningful. The random‐effects summary was treated as the average range of possible treatment effects and we discussed the clinical implications of treatment effects differing between trials. If the average treatment effect was not clinically meaningful, we did not combine trials. Where we used random‐effects analyses, we presented the results as the average treatment effect with 95% confidence intervals, and the estimates of Tau² and I².

Subgroup analysis and investigation of heterogeneity

If we had identified substantial heterogeneity, we planned to investigate it using subgroup analyses and sensitivity analyses. We would have considered whether an overall summary was meaningful, and if it was, used a random‐effects analysis to produce it.

For the primary outcomes, where data were available, we planned the following subgroup analyses.

Spontaneous labour versus induced labour.
Primiparous versus multiparous.
Continuous support in labour versus no continuous support.

We were unable to perform any of the planned subgroup analyses due to lack of data relating to subgroups.

In future updates, if subgroup analyses are performed, we will assess subgroup differences by interaction tests available within RevMan (RevMan 2014). We will report the results of subgroup analyses quoting the Chi² statistic and P value, and the interaction test I² value.

Sensitivity analysis

We carried out sensitivity analyses to explore the effect of trial quality assessed by concealment of allocation, high attrition rates, or both. We excluded trials assessed to be at high risk of selection bias (allocation concealment), attrition bias, or both from the analyses in order to assess whether this made any difference to the overall results of the review's primary outcomes.

Results

Description of studies

Results of the search

See: Figure 1

For this update, we retrieved 17 relevant trial reports and we also reassessed the two trial reports (Malarewicz 2005; Torkamani 2010) that were awaiting further classification in the previous version of the review (Cluett 2009). Of these, we included three trials (five reports) (Gayiti 2015; Ghasemi 2013; Torkamani 2010), and added an additional report each to Rush 1996 and Woodward 2004. One trial is ongoing, for which we have requested information on completion (Dabiri 2016), and we excluded eight trials (11 reports). We have now included 15 trials (Cammu 1994; Chaichian 2009; Da Silva 2006; Eckert 2001; Eriksson 1997; Gayiti 2015; Ghasemi 2013; Kuusela 1998; Nikodem 1999; Ohlsson 2001; Rush 1996; Schorn 1993; Taha 2000; Torkamani 2010; Woodward 2004).

Included studies

Design

All included trials are randomised controlled trials (Cammu 1994; Chaichian 2009; Da Silva 2006; Eckert 2001; Eriksson 1997; Gayiti 2015; Ghasemi 2013; Kuusela 1998; Nikodem 1999; Ohlsson 2001; Rush 1996; Schorn 1993; Taha 2000; Torkamani 2010; Woodward 2004).

Sample sizes

Sample size ranged from 33 (Kuusela 1998) to 800 (Rush 1996).

Setting and dates of trials

The trials were conducted across a wide range of countries: Belgium (Cammu 1994), Iran (Chaichian 2009; Ghasemi 2013; Torkamani 2010), Brazil (Da Silva 2006), Australia (Eckert 2001), Sweden (Eriksson 1997; Ohlsson 2001), China (Gayiti 2015), Finland (Kuusela 1998), South Africa (Nikodem 1999; Taha 2000), Canada (Rush 1996), the USA (Schorn 1993), and the UK (Woodward 2004).

All trials were undertaken in a hospital labour ward setting, with varying degree of medical intervention considered as routine practice, for example the use of enemas and shaves (Gayiti 2015), intravenous access and postpartum oxytocin (Ghasemi 2013), other trials did not indicate the underpinning approach to care. In particular, one‐to‐one care in labour is known to affect labour outcomes (Hodnett 2013), and this was clearly documented in only four trials (Cammu 1994; Da Silva 2006; Nikodem 1999; Taha 2000). Where it was stated that normal/routine/standard care was provided, this was understood to mean that the practitioners who normally provided intrapartum care to women in labour in the study centre provided care for the study participants (Da Silva 2006; Eckert 2001; Eriksson 1997; Ghasemi 2013; Nikodem 1999; Rush 1996; Schorn 1993; Woodward 2004). Cammu 1994 indicated that care was supervised by obstetric staff.

Of the trials that reported trial dates, six trials took place between 1990 and 2000 (Eckert 2001 1995 to 1998; Kuusela 1998 1997 to 1998; Nikodem 1999 1999; Ohlsson 2001 1992 to 1995; Rush 1996 1998; Schorn 1993 1990 to 1991), and four took place between 2005 and 2015 (Chaichian 2009 2006 to 2007; Gayiti 2015 2012 to 2013; Ghasemi 2013 2008 to 2009; Torkamani 2010 2006 to 2007).

Participants

Most trial authors did not specify the parity of included women. Three trials only included nulliparous women (Cammu 1994; Da Silva 2006; Gayiti 2015), and one included both multiparous and nulliparous (Woodward 2004).

Interventions and comparisons

Of the 15 trials included in this review, eight related to the first stage of labour only (Cammu 1994; Da Silva 2006; Eckert 2001; Kuusela 1998; Ohlsson 2001; Rush 1996; Schorn 1993; Taha 2000); one related to early versus late immersion in the first stage of labour (Eriksson 1997); four involved immersion during the first and second stages of labour (Chaichian 2009; Gayiti 2015; Torkamani 2010; Woodward 2004); and two involved women in the second stage of labour only (Ghasemi 2013; Nikodem 1999). There were no studies evaluating the use of different types of baths/pools at any stage of labour or the effects of water immersion on the third stage of labour.

Water temperature, which is known to be important in the care of women using water immersion during labour, also differed between trials. Reporting varied across trials, with some using a temperature up to 37ºC (Cammu 1994; Eckert 2001; Gayiti 2015; Kuusela 1998); others up to 38ºC (Da Silva 2006; Eriksson 1997; Taha 2000); and others not stated (Chaichian 2009; Ghasemi 2013; Nikodem 1999; Ohlsson 2001; Schorn 1993; Torkamani 2010; Woodward 2004). Rush 1996 referred to a temperature of 38ºC to 39ºC. Higher temperatures may affect outcomes, but there are no studies comparing outcomes for the use of different water temperatures.

The variation in practices between study centres and data presentation restricted comparison across studies, resulting in the predominance of one study's findings for several variables particularly in relation to the immersion in water during the second stage of labour, and for all of the outcomes for early versus late immersion, which was compared by Eriksson 1997 only.

There were no trials that compared water immersion with other forms of pain relief as described in Types of interventions.

Outcomes

A wide range of data were collected, and there was wide variation regarding specific outcome measures and their presentation. For example, some studies did not consider neonatal well‐being. Apgar scores were reported differently: some used them as continuous data, others as dichotomous. There were also differences in reporting maternal data, for example labour duration was presented as an overall total or only provided for individual stages of labour.

For further details, seeCharacteristics of included studies.

Funding sources

Woodward 2004 was partly funded by Getting Started in Research Grant from Northampton General Hospital NHS Trust. All the remaining trials did not disclose funding sources.

Declarations of interest

One trial (Gayiti 2015) reported that the authors had no conflicts of interest. All the remaining trials did not mention conflicts of interest.

Excluded studies

We excluded 14 studies.

Bastide 1990 was excluded as the description of the intervention was whirlpool bath and was inadequate to confirm if immersion of the pregnant abdomen was possible. We had only unpublished data, and the authors did not provide additional information.

Benfield 2001 was excluded because the intervention was not water immersion, as the water depth was limited as women lay on a raft and the focus was on psychophysical measures of anxiety in early labour only, and it was not an randomised controlled trial (RCT) and had no comparator ‐ it was a pre‐test, post‐test trial.

One pilot study (Calvert 2000), was excluded because its objective was to compare the effect of essential oil of ginger with the essential oil of lemon grass added to a birthing pool, not the water immersion itself.

In two studies by Cluett (Cluett 2001; Cluett 2004), the women were not at low risk of complications as all had been diagnosed as having labour dystocia. These two studies addressed water immersion as a mechanism for addressing dystocia in labour for nullipara.

The trials by Kashanian 2013 and Irion 2011 related to antenatal use of water immersion, and therefore not the intervention being considered in this review.

Labrecque 1999 was excluded because the water group included whirlpool, back massage and ‘liberal mobilisation’ negating the possibility of assessing the effect of water immersion.

We excluded the following studies because they involved inappropriate interventions, using comparisons between women using a shower versus other comparators and therefore they did not immerse in a bath or birthing pool (Henrique 2015; Irion 2011; Khadijeh 2015; Lee 2013).

We excluded Malarewicz 2005 as there was inadequate description of the pool to confirm immersion, and the report only provided data on cervical dilation between two time points, which is a subjective measurement by the caregiver, of a non linear outcome. No data were provided on length of labour which is the outcome used within this review. No other outcome was provided despite direct request to the authors for non published data.

Two studies were excluded as they were not randomised trials (Cai 2005; Zou 2008).

Risk of bias in included studies

See details under Characteristics of included studies, Figure 2; Figure 3.

'Risk of bias' graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.

'Risk of bias' summary: review authors' judgements about each risk of bias item for each included study.

Allocation

We considered random sequence generation to be at low risk of bias for five trials (Da Silva 2006; Eriksson 1997; Rush 1996; Schorn 1993; Woodward 2004) as they used a computer‐generated random number table to generate the random sequence. Three trials were at high risk of bias (Eckert 2001; Nikodem 1999; Taha 2000) because they used blocks for randomisation, with potential for breaking concealment. The remaining seven trials were at unclear risk of bias for random sequence generation because they did not report clearly the method for randomisation.

Similarly for allocation concealment, we judged eight trials to be at low risk of bias as they all reported using sequentially numbered, opaque sealed envelopes (Cammu 1994; Eckert 2001; Eriksson 1997; Nikodem 1999; Ohlsson 2001; Rush 1996; Taha 2000; Woodward 2004). Two were at high risk of bias: Da Silva 2006 only used 'tabs' to cover allocation; and in Schorn 1993, the midwife knew the allocation. The remaining five trials were at unclear risk of bias (Chaichian 2009; Gayiti 2015; Ghasemi 2013; Kuusela 1998; Torkamani 2010) because they did not clearly describe the method for allocation concealment (refer to Figure 2; Figure 3).

Blinding

None of the trials cite any blinding of participants and personnel, and this is likely to be difficult to achieve, as use of water during labour is usually clearly documented in case records, so we have assessed them all as high risk of bias.

As an intervention, it is not possible to blind participants or carers to water immersion. Not all participants and/or carers will be in a state of equipoise between immersion or non‐immersion, that is being equally comfortable and confident about water immersion. This may positively or negatively influence outcomes such as pain perception and hence subsequent analgesia use, maternal satisfaction, self‐esteem and postpartum depression. An example of this is Woodward 2004, which reported that some midwives were apparently not supportive of women using water, suggesting a positive bias within the women, and in this case a negative bias within the midwives. Conversely, Rush 1996 reported practitioners as maintaining an interest in low‐intervention labour practice, suggesting a positive bias towards water immersion. Water immersion, however, is as much a psychological choice as a physical pain‐management strategy, and as such pragmatic clinical trials are assessing the effect of the whole package.

None of the trials cite any blinding of outcome assessment, and while, due to the nature of the intervention which is documented on care records, it is difficult to achieve, it is in theory possible. However, this was not described and so we have assessed all as being at unclear risk of bias.

Incomplete outcome data

We considered compliance with trial allocation to be variable across the trials. We classified eight trials as being at high risk of attrition bias, (Da Silva 2006; Eckert 2001; Eriksson 1997; Ghasemi 2013; Ohlsson 2001; Rush 1996; Torkamani 2010; Woodward 2004), as a known or unknown number of participants did not receive the allocated intervention. Of the trials that involved water immersion in the first stage of labour, Rush 1996 reported that 46% of women allocated to water immersion did not actually enter the water. Woodward 2004 planned a 2:1 ratio allocation to water anticipating that about 50% of women would not use water, but of the 40 allocated to use water, only 24 used the pool. Four (of 58) women in Da Silva 2006 did not receive the water intervention due to medical/obstetric reasons. Another three trials (Eckert 2001; Eriksson 1997; Ohlsson 2001) reported some cross‐over between groups. Analysis of the Torkamani 2010 outcome data in percentages, indicated attrition, as the numbers are not consistent, although this is not explained in the translated trial description available. Ghasemi 2013 data imply attrition of 17 of 100 in the water group and 12 in the traditional care group, but did not provide details. Five studies indicated no attrition (Cammu 1994; Gayiti 2015; Nikodem 1999; Schorn 1993; Taha 2000). Chaichian 2009 and Kuusela 1998 did not provide information on this.

Selective reporting

We judged 10 trials to be at low risk of bias as they appear to have reported all of the data (Cammu 1994; Da Silva 2006; Eckert 2001; Eriksson 1997; Nikodem 1999; Ohlsson 2001; Rush 1996; Schorn 1993; Taha 2000; Woodward 2004). We considered two trials(Chaichian 2009; Torkamani 2010) to be at high risk of bias as it was clear that not all the data were reported; in Torkamani 2010, women who required a caesarean section after apparently consenting and entering the trial were excluded indicating analysis was not by intention‐to‐treat and there were no data on the number of such women in each group. Chaichian 2009 only reported key outcomes, and stated that the rest were not significant. We judged selective reporting bias in three studies as unclear from the available translations (Gayiti 2015; Ghasemi 2013; Kuusela 1998).

Other potential sources of bias

Weclassified all the trials as unclear for other bias as the trials adopted a variety of definitions for water immersion, with different size baths/pools containing different volumes of water. To date, there is no evidence as to whether different degrees of immersion, or the amount of mobility possible within the bath/pool, affect outcomes. Schorn 1993 referred to a tub with a moulded seat, which may restrict mobility and the freedom to adopt different positions while immersed. Likewise, Rush 1996 used a pool where the woman could not change position. Schorn 1993 and Rush 1996 used a whirlpool (hot tub with jets) and the effect of moving water during immersion may be different to the effect of still water. Kuusela 1998 referred to a tub that was 70 cm deep and held 730 litres; Da Silva 2006 indicated tub volume as 194 litres; Eckert 2001 and Eriksson 1997 cite tub depths of 54 cm and 40 cm, respectively. Other trials did not provide a description of the pool used. Differences as to what constitutes water immersion makes comparisons of outcomes across trials difficult.

The duration of immersion in water was very variable. For trials related to the first stage of labour, this ranged from restrictions on length of time in the water of between 30 to 60 minutes (Da Silva 2006; Kuusela 1998, Schorn 1993), to Taha 2000 who indicated women could only be out of the water for a maximum of 30 minutes at any one time during labour. Cammu 1994 and Eckert 2001 specifically indicated there was no restriction, while the other trials did not comment on this.

Women in three trials did not receive the intervention despite being randomised to immersion groups: Rush 1996 reported that 46% of women allocated to water immersion did not enter the water, Woodward 2004 reported that of the 40 allocated to use water, only 24 used the pool, four (of 58) women in Da Silva 2006 did not receive the water intervention due to medical/obstetric reasons. It is not clear if these studies used intention‐to‐treat analysis.

All trials were in hospital‐based settings and had varying degrees of medical models of care, and it was not possible to judge the impact of these on level of bias.

These factors limited comparison across trials and the reliability and validity of the trial findings.

Effects of interventions

See: Table 1; Table 2

Summary of findings for the main comparison. Immersion in water compared to no immersion during first stage of labour in water during labour and birth.

Immersion in water compared to no immersion during first stage of labour in water during labour and birth
Patient or population: women in labour  Setting: hospital‐based maternity units in the following countries: UK, Canada, Iran, Finland, Australia, USA, Belgium, Brazil, Sweden, South Africa and China.  Intervention: immersion in water in the first stage of labour  Comparison: no immersion during first stage of labour
Outcomes	*Anticipated absolute effects^ (95% CI)**		Relative effect  (95% CI)	№ of participants  (studies)	Quality of the evidence  (GRADE)	Comments
	Risk with no immersion during first stage of labour	Risk with immersion in water
Mode of birth (spontaneous vaginal birth)	Study population		RR 1.01  (0.97 to 1.04)	2559  (6 RCTs)	⊕⊕⊕⊝  MODERATE ¹
	822 per 1000	830 per 1000  (797 to 855)
Mode of birth (instrumental vaginal birth)	Study population		RR 0.86 (0.70 to 1.05)	2559 (6 RCTs)	⊕⊕⊝⊝  LOW ^{1 2}
	138 per 1000	119 per 1000 (97 to 1.05)
Mode of birth (caesarean section)	Study population		RR 1.27 (0.91 to 1.79)	2652 (7 RCTs)	⊕⊕⊝⊝  LOW ^{2 3}
	41 per 1000	52 per 1000 (38 to 74)
Use of analgesia (regional)	Study population		RR 0.91  (0.83 to 0.99)	2439  (5 RCTs)	⊕⊕⊕⊝  MODERATE ¹
	429 per 1000	390 per 1000  (356 to 424)
Perineal trauma (third‐ or fourth‐degree tears)	Study population		RR 1.36  (0.85 to 2.18)	2341  (4 RCTs)	⊕⊕⊕⊝  MODERATE ¹
	25 per 1000	33 per 1000  (21 to 54)
Perinatal death	Study population		‐	‐	‐	No trial reported this outcome.
	see comment	see comment
Admission to neonatal intensive care unit	Study population		Average RR 1.30  (0.42 to 3.97)	1511  (2 RCTs)	⊕⊕⊝⊝  LOW ^{2 4}
	58 per 1000	75 per 1000  (24 to 229)
Neonatal infection	Study population		RR 2.00  (0.50 to 7.94)	1295  (5 RCTs)	⊕⊝⊝⊝  VERY LOW ^{1 5}
	5 per 1000	9 per 1000  (2 to 37)
Estimated blood loss (mL)	The mean estimated blood loss with immersion was 265.5 mL	MD 14.33 mL lower without immersion  (63.03 mL lower to 34.37 mL higher)	‐	153  (2 RCTs)	⊕⊝⊝⊝  VERY LOW ^{6 7}
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).    CI: Confidence interval; RR: Risk ratio
GRADE Working Group grades of evidence  High certainty: We are very confident that the true effect lies close to that of the estimate of the effect  Moderate certainty: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different  Low certainty: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect  Very low certainty: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

Date	Event	Description
18 July 2017	New search has been performed	Overall conclusions have not changed.
18 July 2017	New citation required but conclusions have not changed	Search updated, 17 new trial reports identified, plus we reassessed the trials previously awaiting further classification (Malarewicz 2005; Torkamani 2010). We also reviewed all trials assessed in the previous version of our review to confirm inclusion/exclusion. Data from three new trials have been included (Gayiti 2015; Ghasemi 2013; Torkamani 2010). Other trials identified in the search were excluded (Cai 2005; Irion 2011; Henrique 2015; Lee 2013, Kashanian 2013; Khadijeh 2015; Malarewicz 2005; Zou 2008), and one has been added to ongoing study section as to date no outcome data have been available (Dabiri 2016). Text of review updated in all sections, incorporating latest evidence from trials and GRADE analysis, as well as wider literature. Overall, conclusions not changed.
14 December 2011	Amended	Corrected error in Abstract and in Analysis 1.17.
30 June 2011	New search has been performed	Papers from June 2011 search reviewed and data incorporated as appropriate. 1 new study included (Chaichian 2009) and 2 added to Characteristics of studies awaiting classification pending more information from the authors. Risk of bias tables generated. Text updated, although no change in overall conclusions.
5 January 2009	New citation required but conclusions have not changed	Change in authorship.
20 November 2008	Feedback has been incorporated	Response from authors to feedback from Wein incorporated.
20 November 2008	New search has been performed	Search updated. New trials identified, appraised and data are included. Title changed to reflect focus on water immersion in labour and birth, so pregnancy removed from title, and outcomes updated accordingly. Background information updated. Results and discussion sections updated but no change to overall conclusions.
29 October 2008	Amended	Converted to new review format.
25 April 2004	New search has been performed	Search updated. Five new trials are included (Eckert 2001; Eriksson 1997; Nikodem 1999; Ohlsson 2001; Taha 2000).
25 April 2004	New citation required and conclusions have changed	The inclusion of the new trials has resulted in a change in the implications for practice, which now indicates that immersion in water during the first stage of labour reduces reported maternal pain and the use of analgesia.    The outcome measures have been modified to ensure clarity. Neonatal outcomes have been added to reflect current methods of wellbeing assessment. Change in authorship for this update.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Mode of birth (spontaneous vaginal birth)	6	2559	Risk Ratio (M‐H, Fixed, 95% CI)	1.01 [0.97, 1.04]
2 Mode of birth (instrumental vaginal births)	6	2559	Risk Ratio (M‐H, Fixed, 95% CI)	0.86 [0.70, 1.05]
3 Mode of birth (caesarean section)	7	2652	Risk Ratio (M‐H, Fixed, 95% CI)	1.27 [0.91, 1.79]
4 Use of analgesia (regional)	5	2439	Risk Ratio (M‐H, Fixed, 95% CI)	0.91 [0.83, 0.99]
5 Perineal trauma (third‐ or fourth‐degree tears)	4	2341	Risk Ratio (M‐H, Fixed, 95% CI)	1.36 [0.85, 2.18]
6 Admission to neonatal intensive care unit	2	1511	Risk Ratio (M‐H, Random, 95% CI)	1.30 [0.42, 3.97]
7 Neonatal infection	5	1295	Risk Ratio (M‐H, Fixed, 95% CI)	2.00 [0.50, 7.94]
8 Neonate temperature	1		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
8.1 Temperature greater than 37.8 degrees C as an indicator for infection	1	274	Risk Ratio (M‐H, Fixed, 95% CI)	1.0 [0.06, 15.83]
9 Estimated blood loss (mL)	2	153	Mean Difference (IV, Fixed, 95% CI)	‐14.33 [‐63.03, 34.37]
10 Postpartum haemorrhage	1	274	Risk Ratio (M‐H, Fixed, 95% CI)	1.58 [0.80, 3.13]
11 Use of analgesia (pharmacological ‐ pethidine/narcotic)	3	1180	Risk Ratio (M‐H, Random, 95% CI)	1.08 [0.59, 1.96]
12 Use of any analgesia	3	487	Risk Ratio (M‐H, Fixed, 95% CI)	0.99 [0.88, 1.12]
13 Use of analgesia (pharmacological ‐ any)	2	394	Risk Ratio (M‐H, Fixed, 95% CI)	1.05 [0.80, 1.39]
14 Maternal infection during labour/postnatal period (perineal, systemic, uterine or increase in temperature)	5	1295	Risk Ratio (M‐H, Fixed, 95% CI)	0.99 [0.50, 1.96]
15 Artificial rupture of membranes	3	926	Risk Ratio (M‐H, Fixed, 95% CI)	1.02 [0.90, 1.16]
16 Use of oxytocin for augmentation of labour	4	1019	Risk Ratio (M‐H, Fixed, 95% CI)	0.91 [0.72, 1.15]
17 Use of non‐pharmacological analgesia (transcutaneous nerve stimulation (TENS)	1	785	Risk Ratio (M‐H, Fixed, 95% CI)	1.25 [0.34, 4.61]
18 Duration of first stage (minutes)	5	1295	Mean Difference (IV, Fixed, 95% CI)	‐11.53 [‐45.42, 22.36]
19 Duration of second stage (minutes)	6	1403	Mean Difference (IV, Random, 95% CI)	1.12 [‐5.23, 7.48]
20 Duration of third stage (minutes)	2	1059	Mean Difference (IV, Fixed, 95% CI)	0.25 [‐1.10, 1.60]
21 Duration of total labour (all three stages minutes)	1	120	Mean Difference (IV, Fixed, 95% CI)	‐27.5 [‐133.05, 78.05]
22 Perineal trauma (intact)	4	1277	Risk Ratio (M‐H, Fixed, 95% CI)	1.17 [1.01, 1.37]
23 Perineal trauma (second‐degree tears)	4	1212	Risk Ratio (M‐H, Fixed, 95% CI)	0.94 [0.74, 1.20]
24 Perineal trauma (episiotomy)	4	1212	Risk Ratio (M‐H, Fixed, 95% CI)	0.94 [0.80, 1.09]
25 Self reports pain score on visual analogue scale of 0‐10	2		Mean Difference (IV, Random, 95% CI)	Subtotals only
25.1 Pain score at start of assessment period (time zero)	2	141	Mean Difference (IV, Random, 95% CI)	0.15 [‐0.79, 1.08]
25.2 Pain score up to 60 minutes later	2	141	Mean Difference (IV, Random, 95% CI)	‐0.81 [‐1.34, ‐0.28]
26 Pain intensity (experience of moderate to severe pain)	1		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
26.1 Ordinal description as moderate to severe, 30 mins after randomisation	1	120	Risk Ratio (M‐H, Fixed, 95% CI)	0.75 [0.62, 0.91]
26.2 VAS scale 8 to 10, 30 mins after randomisation	1	120	Risk Ratio (M‐H, Fixed, 95% CI)	0.72 [0.58, 0.90]
26.3 Ordinal scale pain faces 4 to 5, 30 mins after randomisation	1	120	Risk Ratio (M‐H, Fixed, 95% CI)	0.67 [0.51, 0.90]
26.4 Ordinal description as moderate to severe, 1 hr after randomisation	1	117	Risk Ratio (M‐H, Fixed, 95% CI)	0.76 [0.63, 0.91]
26.5 VAS scale 8 to 10, 1 hr after randomisation	1	117	Risk Ratio (M‐H, Fixed, 95% CI)	1.21 [0.69, 2.11]
26.6 Ordinal scale pain faces 4 to 5, 1 hr after randomisation	1	117	Risk Ratio (M‐H, Fixed, 95% CI)	0.68 [0.53, 0.86]
26.7 Ordinal description as moderate to severe, 2 hrs after randomisation	1	57	Risk Ratio (M‐H, Fixed, 95% CI)	0.76 [0.59, 0.98]
26.8 VAS scale 8 to 10, 2 hrs after randomisation	1	57	Risk Ratio (M‐H, Fixed, 95% CI)	0.83 [0.66, 1.05]
26.9 Ordinal scale pain faces 4 to 5, 2 hrs after randomisation	1	57	Risk Ratio (M‐H, Fixed, 95% CI)	0.72 [0.52, 0.98]
26.10 Ordinal description as moderate to severe, 3 hrs after randomisation	1	32	Risk Ratio (M‐H, Fixed, 95% CI)	0.52 [0.23, 1.16]
26.11 VAS scale 8 to 10, 3 hrs after randomisation	1	32	Risk Ratio (M‐H, Fixed, 95% CI)	0.69 [0.39, 1.23]
26.12 Ordinal scale pain faces 4 to 5, 3 hrs after randomisation	1	32	Risk Ratio (M‐H, Fixed, 95% CI)	0.57 [0.25, 1.27]
26.13 Ordinal description as moderate to severe, 24 hrs after randomisation	1	119	Risk Ratio (M‐H, Fixed, 95% CI)	0.64 [0.50, 0.82]
26.14 VAS scale 8 to 10, 24 hrs after randomisation	1	119	Risk Ratio (M‐H, Fixed, 95% CI)	0.62 [0.49, 0.80]
26.15 Ordinal scale pain faces 4 to 5, 24 hrs after randomisation	1	119	Risk Ratio (M‐H, Fixed, 95% CI)	0.69 [0.54, 0.87]
27 Systolic blood pressure	1	120	Mean Difference (IV, Fixed, 95% CI)	‐7.20 [‐13.12, ‐1.28]
28 Diastolic blood pressure	1	120	Mean Difference (IV, Fixed, 95% CI)	‐10.20 [‐13.70, ‐6.70]
29 Mean arterial blood pressure	1	120	Mean Difference (IV, Fixed, 95% CI)	‐10.5 [‐14.68, ‐6.32]
30 Preference for care in subsequent labour (Does not wish to use bath with next labour/birth)	1	119	Risk Ratio (M‐H, Fixed, 95% CI)	0.38 [0.14, 0.98]
31 Postpartum depression (EPDS more than 11)	2	370	Risk Ratio (M‐H, Fixed, 95% CI)	1.38 [0.85, 2.24]
32 Abnormal fetal heart rate patterns	3	487	Risk Ratio (M‐H, Random, 95% CI)	0.75 [0.34, 1.67]
33 Presence of meconium‐stained liquor	4	1200	Risk Ratio (M‐H, Random, 95% CI)	0.92 [0.64, 1.33]
34 Apgar score less than seven at five minutes	5	1834	Risk Ratio (M‐H, Fixed, 95% CI)	1.58 [0.63, 3.93]
35 Apgar score at five minutes	2	893	Mean Difference (IV, Fixed, 95% CI)	‐0.03 [‐0.11, 0.06]
36 Umbilical artery pH less than 7.20	1	110	Risk Ratio (M‐H, Fixed, 95% CI)	5.18 [0.25, 105.51]
37 Breastfeeding ‐ not breastfeeding after six weeks post birth	2	363	Risk Ratio (M‐H, Fixed, 95% CI)	1.17 [0.64, 2.15]

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Mode of birth (spontaneous vaginal birth)	1	120	Risk Ratio (M‐H, Fixed, 95% CI)	1.02 [0.96, 1.08]
2 Mode of birth (instrumental vaginal births)	1	120	Risk Ratio (M‐H, Fixed, 95% CI)	1.0 [0.06, 15.62]
3 Mode of birth (caesarean section)	1	120	Risk Ratio (M‐H, Fixed, 95% CI)	0.33 [0.01, 8.02]
4 Perinatal deaths	1	120	Risk Ratio (M‐H, Fixed, 95% CI)	3.0 [0.12, 72.20]
5 Admission to neonatal intensive care unit	2	291	Risk Ratio (M‐H, Fixed, 95% CI)	0.78 [0.38, 1.59]
6 Neonate temperature	1		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
6.1 Temperature less than 36.2 degrees C at birth	1	109	Risk Ratio (M‐H, Fixed, 95% CI)	0.98 [0.30, 3.20]
6.2 Temperature greater than 37.5 degrees C at birth	1	109	Risk Ratio (M‐H, Fixed, 95% CI)	2.62 [0.73, 9.35]
7 Fever reported in first week	1	171	Risk Ratio (M‐H, Fixed, 95% CI)	0.53 [0.10, 2.82]
8 Postpartum haemorrhage more than 500 mL	1	120	Risk Ratio (M‐H, Fixed, 95% CI)	0.14 [0.01, 2.71]
9 Duration of second stage (minutes)	2	291	Mean Difference (IV, Fixed, 95% CI)	‐1.83 [‐8.18, 4.52]
10 Perineal trauma (episiotomy)	1	119	Risk Ratio (M‐H, Fixed, 95% CI)	0.74 [0.17, 3.15]
11 Perineal trauma (second degree tear)	1	119	Risk Ratio (M‐H, Fixed, 95% CI)	1.16 [0.57, 2.38]
12 Experience of moderate to severe pain	1	117	Risk Ratio (M‐H, Fixed, 95% CI)	1.06 [0.73, 1.53]
12.1 Ordinal description as moderate to severe	1	117	Risk Ratio (M‐H, Fixed, 95% CI)	1.06 [0.73, 1.53]
13 Preference for care in subsequent labour (Does not wish to use bath next birth)	1	117	Risk Ratio (M‐H, Fixed, 95% CI)	0.57 [0.22, 1.47]
14 Satisfied with labour	1	117	Risk Ratio (M‐H, Fixed, 95% CI)	0.24 [0.07, 0.80]
14.1 Little or not satisfied with coping experience	1	117	Risk Ratio (M‐H, Fixed, 95% CI)	0.24 [0.07, 0.80]
15 Presence of meconium‐stained liquor	1	120	Risk Ratio (M‐H, Fixed, 95% CI)	1.4 [0.47, 4.17]
16 Apgar score less than seven (five minutes)	1	119	Risk Ratio (M‐H, Fixed, 95% CI)	4.92 [0.24, 100.31]
17 Mean Apgar at five minutes	1	171	Mean Difference (IV, Fixed, 95% CI)	‐0.10 [‐0.22, 0.02]
18 Umbilical artery pH less than 7.20	1	116	Risk Ratio (M‐H, Fixed, 95% CI)	0.89 [0.45, 1.75]

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Mode of birth (spontaneous vaginal birth)	9	2845	Risk Ratio (M‐H, Random, 95% CI)	1.03 [0.99, 1.09]
2 Mode of birth (instrumental vaginal births)	8	2739	Risk Ratio (M‐H, Fixed, 95% CI)	0.86 [0.70, 1.04]
3 Mode of birth (caesarean section)	9	2832	Risk Ratio (M‐H, Fixed, 95% CI)	1.19 [0.86, 1.65]
4 Use of analgesia (regional)	6	2499	Risk Ratio (M‐H, Fixed, 95% CI)	0.90 [0.82, 0.98]
5 Perineal trauma (third‐ or fourth‐degree tears)	5	2401	Risk Ratio (M‐H, Fixed, 95% CI)	1.37 [0.86, 2.17]
6 Perinatal deaths	1	120	Risk Ratio (M‐H, Fixed, 95% CI)	3.0 [0.12, 72.20]
7 Admission to neonatal intensive care unit	5	1862	Risk Ratio (M‐H, Fixed, 95% CI)	0.99 [0.70, 1.39]
8 Neonatal infection	5	1295	Risk Ratio (M‐H, Fixed, 95% CI)	2.00 [0.50, 7.94]
9 Neonate temperature	2		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
9.1 Temperature greater than 37.8 degrees C as an indicator for infection	1	274	Risk Ratio (M‐H, Fixed, 95% CI)	1.0 [0.06, 15.83]
9.2 Temperature less than 36.2 degrees C at birth	1	109	Risk Ratio (M‐H, Fixed, 95% CI)	0.98 [0.30, 3.20]
9.3 Temperature greater than 37.5 degrees C at birth	1	109	Risk Ratio (M‐H, Fixed, 95% CI)	2.62 [0.73, 9.35]
10 Fever reported in first week	1	171	Risk Ratio (M‐H, Fixed, 95% CI)	0.53 [0.10, 2.82]
11 Antibiotics given to neonate	1	60	Risk Ratio (M‐H, Fixed, 95% CI)	1.5 [0.17, 13.52]
12 Estimated blood loss (mL)	3	273	Mean Difference (IV, Fixed, 95% CI)	‐6.28 [‐13.67, 1.11]
13 Postpartum haemorrhage	2	394	Risk Ratio (M‐H, Random, 95% CI)	0.73 [0.08, 6.90]
14 Use of analgesia (pharmacological ‐ pethidine/narcotic)	4	1240	Risk Ratio (M‐H, Random, 95% CI)	0.85 [0.46, 1.56]
15 Use of analgesia (pharmacological ‐ any)	2	394	Risk Ratio (M‐H, Fixed, 95% CI)	1.05 [0.80, 1.39]
16 Use of any analgesia	5	653	Risk Ratio (M‐H, Random, 95% CI)	0.72 [0.46, 1.12]
17 Maternal infection during labour/postnatal period (perineal, systemic, uterine or increase in temperature)	5	1295	Risk Ratio (M‐H, Fixed, 95% CI)	0.99 [0.50, 1.96]
18 Artificial rupture of membranes	3	926	Risk Ratio (M‐H, Fixed, 95% CI)	1.02 [0.90, 1.16]
19 Use of oxytocin for augmentation of labour	5	1125	Risk Ratio (M‐H, Random, 95% CI)	0.64 [0.32, 1.28]
20 Use of non‐pharmacological analgesia (transcutaneous nerve stimulation (TENS))	2	845	Risk Ratio (M‐H, Fixed, 95% CI)	1.05 [0.37, 2.94]
21 Duration of first stage (minutes)	8	1561	Mean Difference (IV, Random, 95% CI)	‐42.21 [‐80.93, ‐3.49]
22 Duration of second stage (minutes)	11	1960	Mean Difference (IV, Random, 95% CI)	‐2.85 [‐8.85, 3.16]
23 Duration of third stage (minutes)	3	1165	Mean Difference (IV, Random, 95% CI)	‐0.52 [‐1.84, 0.79]
24 Duration of total labour (all three stages)	2	240	Mean Difference (IV, Fixed, 95% CI)	‐40.83 [‐87.09, 5.43]
25 Perineal trauma (none‐ intact)	5	1337	Risk Ratio (M‐H, Fixed, 95% CI)	1.16 [0.99, 1.35]
26 Perineal trauma (first‐ and second‐degree tears)	7		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
26.1 Second‐degree tear	7	1525	Risk Ratio (M‐H, Fixed, 95% CI)	0.89 [0.71, 1.10]
27 Perineal trauma (episiotomy)	7	1511	Risk Ratio (M‐H, Random, 95% CI)	0.88 [0.67, 1.17]
28 Self reports pain score on visual analogue scale of 0‐10	3		Mean Difference (IV, Random, 95% CI)	Subtotals only
28.1 Pain score at start of assessment period (time zero)	2	141	Mean Difference (IV, Random, 95% CI)	0.15 [‐0.79, 1.08]
28.2 Pain score up to 60 minutes later	2	141	Mean Difference (IV, Random, 95% CI)	‐0.81 [‐1.34, ‐0.28]
28.3 overall pain score (assessed once post labour)	1	100	Mean Difference (IV, Random, 95% CI)	‐3.43 [‐3.95, ‐2.91]
29 Pain intensity (experience of moderate to severe pain)	2		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
29.1 Ordinal description as moderate to severe, 30 mins after randomisation	1	120	Risk Ratio (M‐H, Fixed, 95% CI)	0.75 [0.62, 0.91]
29.2 VAS scale 8 to 10, 30 mins after randomisation	1	120	Risk Ratio (M‐H, Fixed, 95% CI)	0.72 [0.58, 0.90]
29.3 Ordinal scale pain faces 4 to 5, 30 mins after randomisation	1	120	Risk Ratio (M‐H, Fixed, 95% CI)	0.67 [0.51, 0.90]
29.4 Ordinal description as moderate to severe, 1 hr after randomisation	1	117	Risk Ratio (M‐H, Fixed, 95% CI)	0.76 [0.63, 0.91]
29.5 VAS scale 8 to 10, 1 hr after randomisation	1	117	Risk Ratio (M‐H, Fixed, 95% CI)	1.21 [0.69, 2.11]
29.6 Ordinal scale pain faces 4 to 5, 1 hr after randomisation	1	117	Risk Ratio (M‐H, Fixed, 95% CI)	0.68 [0.53, 0.86]
29.7 Ordinal description as moderate to severe, 2 hrs after randomisation	1	57	Risk Ratio (M‐H, Fixed, 95% CI)	0.76 [0.59, 0.98]
29.8 VAS scale 8 to 10, 2 hrs after randomisation	1	57	Risk Ratio (M‐H, Fixed, 95% CI)	0.83 [0.66, 1.05]
29.9 Ordinal scale pain faces 4 to 5, 2 hrs after randomisation	1	57	Risk Ratio (M‐H, Fixed, 95% CI)	0.72 [0.52, 0.98]
29.10 Ordinal description as moderate to severe, 3 hrs after randomisation	1	32	Risk Ratio (M‐H, Fixed, 95% CI)	0.52 [0.23, 1.16]
29.11 VAS scale 8 to 10, 3 hrs after randomisation	1	32	Risk Ratio (M‐H, Fixed, 95% CI)	0.69 [0.39, 1.23]
29.12 Ordinal scale pain faces 4 to 5, 3 hrs after randomisation	1	32	Risk Ratio (M‐H, Fixed, 95% CI)	0.57 [0.25, 1.27]
29.13 Ordinal description as moderate to severe, 24 hrs after randomisation	1	119	Risk Ratio (M‐H, Fixed, 95% CI)	0.64 [0.50, 0.82]
29.14 VAS scale 8 to 10, 24 hrs after randomisation	1	119	Risk Ratio (M‐H, Fixed, 95% CI)	0.62 [0.49, 0.80]
29.15 Ordinal scale pain faces 4 to 5, 24 hrs after randomisation	1	119	Risk Ratio (M‐H, Fixed, 95% CI)	0.69 [0.54, 0.87]
29.16 Ordinal description as moderate to severe	1	117	Risk Ratio (M‐H, Fixed, 95% CI)	1.06 [0.73, 1.53]
30 Maternal temperature	1	60	Mean Difference (IV, Fixed, 95% CI)	0.20 [‐0.18, 0.58]
31 Systolic blood pressure	1	120	Mean Difference (IV, Fixed, 95% CI)	‐7.20 [‐13.12, ‐1.28]
32 Diastolic blood pressure	1	120	Mean Difference (IV, Fixed, 95% CI)	‐10.20 [‐13.70, ‐6.70]
33 Mean arterial blood pressure	1	120	Mean Difference (IV, Fixed, 95% CI)	‐10.5 [‐14.68, ‐6.32]
34 Preference for care in subsequent labour (Does not wish to use bath with next labour/birth)	2	236	Risk Ratio (M‐H, Fixed, 95% CI)	0.46 [0.24, 0.90]
35 Satisfied with labour	1	117	Risk Ratio (M‐H, Fixed, 95% CI)	0.24 [0.07, 0.80]
35.1 Little or not satisfied with coping experience	1	117	Risk Ratio (M‐H, Fixed, 95% CI)	0.24 [0.07, 0.80]
36 Satisfied with labour on scale	1	60	Mean Difference (IV, Fixed, 95% CI)	0.03 [‐0.64, 0.70]
37 Postpartum depression (EPDS more than 11)	2	370	Risk Ratio (M‐H, Fixed, 95% CI)	1.38 [0.85, 2.24]
38 Abnormal fetal heart rate patterns	3	487	Risk Ratio (M‐H, Random, 95% CI)	0.75 [0.34, 1.67]
39 Presence of meconium‐stained liquor	6	1380	Risk Ratio (M‐H, Fixed, 95% CI)	0.97 [0.78, 1.21]
40 Apgar score less than seven at five minutes	6	1953	Risk Ratio (M‐H, Fixed, 95% CI)	1.79 [0.76, 4.25]
41 Apgar score at five minutes	4	1184	Mean Difference (IV, Fixed, 95% CI)	‐0.04 [‐0.11, 0.02]
42 Umbilical artery pH less than 7.20	2	226	Risk Ratio (M‐H, Fixed, 95% CI)	1.04 [0.54, 1.98]
43 Breastfeeding	1	60	Risk Ratio (M‐H, Fixed, 95% CI)	0.86 [0.69, 1.08]
44 Not breastfeeding after six weeks post birth	2	363	Risk Ratio (M‐H, Fixed, 95% CI)	1.17 [0.64, 2.15]

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Use of pharmacological analgesia (epidural/spinal analgesia/paracervical block)	1	200	Risk Ratio (M‐H, Fixed, 95% CI)	2.21 [1.39, 3.52]
2 Neonatal infection	1	200	Risk Ratio (M‐H, Fixed, 95% CI)	3.0 [0.12, 72.77]
3 Use of oxytocin	1	200	Risk Ratio (M‐H, Fixed, 95% CI)	1.9 [1.35, 2.68]
4 Abnormal fetal heart rate patterns	1	200	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
5 Apgar score less than seven at one minute	1	200	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]

Methods	Randomisation by sealed opaque envelopes containing method indicator card Methodological qualities: selection bias: low risk: adequate concealment at time of randomisation; performance bias: high risk of bias could have been introduced because researcher could not be blind to group allocation after randomisation; exclusion bias: moderate risk of bias: 57 were randomly allocated to bath, 3 refused to bathe and their results were not included in analyses; bias conclusion: moderate bias: 1 or more criteria partially met. May raise some doubt about the results.
Participants	Study group: n = 54. Control group: n = 56 Inclusion criteria: gestation > 36 weeks; low risk; nulliparous; singleton; cephalic presentation; active labour between 4 cm to 5 cm cervical dilatation; ruptured membranes with clear liquor on entry; scalp electrodes used for all participants; ambulation and analgesics were allowed.
Interventions	Immersion in labour during the first stage of labour Pool described as an oval‐shaped hot tub. Bath temperature not exceeding 37 degrees celsius. No chemicals added  Control group: no water immersion during labour Women in both groups received 'personalised' care but it is not clear if this was 1‐to‐1 care or not, although care overseen by obstetricians and all births conducted by house officers (doctors).
Outcomes	Maternal outcomes: use of analgesia/anaesthesia; augmentation of labour; cervical dilatation; duration of labour and birth; mode of delivery; maternal infection. Fetal outcomes:* abnormal FHR patterns needing intervention; neonatal outcomes: neonatal condition; admittance to NICU or high dependency care unit; *neonatal infection rates.
Notes	Academic hospital, Brussels, Belgium Dates of trial: not clear Funding: not reported Declaration of interest: not reported
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No indication of how random sequence was generated
Allocation concealment (selection bias)	Low risk	Sealed opaque envelopes containing method indicator card
Blinding of participants and personnel (performance bias)   All outcomes	High risk	High risk of bias could have been introduced because women, carers and researcher could not be blind to group allocation after randomisation due to the nature of the intervention
Blinding of outcome assessment (detection bias)   All outcomes	Unclear risk	No information provided
Incomplete outcome data (attrition bias)   All outcomes	Low risk	Information available on number of participants asked (water ‐57/control ‐56) to number who gave consent (water ‐53/control ‐56) to outcome data ‐ no attrition
Selective reporting (reporting bias)	Low risk	All outcome detailed in methods are reported on
Other bias	Unclear risk	It is not clear if women had 1‐to‐1 care, which is known to affect outcomes, but is common for water immersion care

Methods	Randomised control trial; no information on how randomisation was achieved
Participants	Water group ‐ n = 53; control group ‐ n = 53 Inclusion criteria: gestational age 37‐42 weeks; no previous CS; intact membranes; no malpresentations; no placenta abruption or praevia; well fetus.
Interventions	Immersion in water during first and second stage of labour Information given to women in pregnancy, then randomised to experimental or control group in labour. Water group labour and birth in warm water pool, but no description of pool size or care protocol given. Control group conventional care at the hospital, but not detailed
Outcomes	Data provided on baseline characteristics or age, gravida, parity, previous abortion, and prolonged rupture of membranes Data provided on outcomes, normal birth rate, duration of labour, use of oxytocin and analgesia (not stated what type) Data collected on episiotomy/perineal trauma, neonatal weight, *Apgar score, gender and breastfeeding initiation but data not given
Notes	Study undertaken in Iranian hospital affiliated to Iran University of Medical Sciences, between June 2006 and September 2007 Authors contacted twice for further information but no reply Funding: not reported Declaration of interest: not reported
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No information given on randomisation processes
Allocation concealment (selection bias)	Unclear risk	No information given on randomisation processes
Blinding of participants and personnel (performance bias)   All outcomes	High risk	High risk of bias could have been introduced because women, carers and researcher could not be blind to group allocation after randomisation due to the nature of the intervention
Blinding of outcome assessment (detection bias)   All outcomes	Unclear risk	No information provided
Incomplete outcome data (attrition bias)   All outcomes	Unclear risk	No indication of women who withdrew from study, or that data were lost/incomplete
Selective reporting (reporting bias)	High risk	Outcomes not detailed on perineal trauma, neonatal weight, Apgar scores, gender and breastfeeding initiation although data collected and described as not significantly different
Other bias	Unclear risk	It is surprising that all the women who went to water gave birth in the water. Normally one would expect some who laboured in water to choose to get out for birth, but no evidence of this as number in each group is the same. This calls into question if all who got into the pool are included in study or just those who remained in for birth as well.

Methods	Randomisation was computer‐generated, and then recorded on a list (paper copy), where the next allocation was concealed from the research until the next woman had provided consent, was recruited and thus being allocated.  Methodological qualities: selection bias: none apparent; performance bias: high risk of bias could have been introduced because researcher could not be blind to group allocation after randomisation; exclusion bias: low risk of bias 4 of 58 in water group did not get water as required CS prior to immersion, and 2 of 56 in control group also required CS prior to reaching cervical dilation of 6 cm Analysed according to ITT; bias conclusion: high risk of bias, where 1 or more criteria are not met may cause plausible bias that seriously weakens confidence in the results.
Participants	Power calculation undertaken Water n = 58 Control n = 56 Full term, nulliparous, live, cephalic presentation, no complications, cervical dilation of 6 cm or less in established labour
Interventions	Immersion in water during first stage of labour Control group received standard care, including cardiotocography on admission, ambulation, amniotomy and oxytocin augmentation if now cervical progress over 3 hours, intermittent auscultation during labour Intervention group as above with immersion in water when cervix had reached 6 cm to 7 cm dilated, for 60 minutes First stage of labour study, all women received 1‐to‐1 care from the researcher Pool was 194 litres, equipped with a heater. Water temperature ranged from 27 to 38 degrees Celsius.
Outcomes	Pain score on 5‐point behavioural scale and numerical pain score from 0 to 10, at 6 cm to 7 cm dilated and again 1 hour later. In addition, the following data were collected: use of augmentation, amniotic liquor conditions, duration of labour, perineal condition, gestational age, Apgar score at 1 and 5 minutes, maternal and water temperature.
Notes	Study done in Sao Paulo, Brazil Dates of trial: not reported Funding: not reported Declaration of interest: not reported
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated random list
Allocation concealment (selection bias)	High risk	Each allocation on the list was covered with a tab, which was removed by the researcher after consent form signed by next participant. This description suggests the process could be open to tampering.
Blinding of participants and personnel (performance bias)   All outcomes	High risk	High risk of bias could have been introduced because women, carers and researcher could not blind to group allocation after randomisation due to the nature of the intervention.
Blinding of outcome assessment (detection bias)   All outcomes	Unclear risk	No information provided
Incomplete outcome data (attrition bias)   All outcomes	High risk	Flow chart detailed participants from eligibility to completion; no attrition after instigation of allocated care, however not all women received the allocated intervention.
Selective reporting (reporting bias)	Low risk	All the data mentioned in the methods, and that would reasonably be expected of this study are reported.
Other bias	Unclear risk	All women had 1‐to‐1 care, which is known to affect outcomes, but is common for water immersion care. In this study the care was from the researcher, regardless of group.

Methods	Randomisation by sealed opaque, sequentially numbered envelopes that were kept in the admission ward. Prepared in random blocks of 10, stratified for parity.  Methodological qualities: selection bias: none; performance bias: high risk of bias could have been introduced because researcher could not be blind to group allocation after randomisation; exclusion bias: high risk of bias 37/134 of women allocated to bath group did not bathe and 34/134 of women allocated to the control group did bathe. Analysed according to ITT; bias conclusion: high risk of bias, where 1 or more criteria are not met may cause plausible bias that seriously weakens confidence in the results.
Participants	Study group n = 137. Control group n = 137  Inclusion criteria: gestation > 36 weeks; low risk; singleton; cephalic presentation. Exclusion criteria: planned CS; history of Group B streptococcal infection; epidural anaesthesia; continuous FHR monitoring needed.
Interventions	Immersion in water during first stage of labour. Women were allocated to a delivery suite with a bath or to a general delivery suite without a bath. The bath group was allowed to use the bath as long as each woman wished, but they had to get out during second stage of labour (first stage only). The bath tub was 120 cm x 160 cm x 54 cm and the maximum water temperature was 37 degrees Celsius.  Control group was allowed to use a shower. First stage only study women received care from same midwives but no mention of 1‐to‐1 second care or not.
Outcomes	Maternal outcomes: 1. maternal experience and satisfaction of labour; 2. use of analgesia/anaesthesia; 3. augmentation of labour; 4. presence of meconium‐stained liquor; 5. duration of labour and birth; 6. mode of delivery; 7. trauma to the birth canal requiring suturing; 8. blood loss ‐ only as percentage of whole; group no event data by group; 9. postpartum depression; 10. breastfeeding. Fetal outcomes:* abnormal FHR patterns, needing intervention. Neonatal outcomes:* neonatal condition; admittance to NICU or high‐dependency care unit; * temperature at birth; *neonatal infection rates.
Notes	Tertiary referral hospital in Adelaide, Australia. May 1995‐Sept 1998  Some of the results are not in an appropriate format. Further information needed Funding: not reported Declaration of interest: not reported
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Random table of numbers, using variable blocks of 10, by a clerk independent of the study. Stratification was by place of birth, hospital or midwifery birth centre.
Allocation concealment (selection bias)	Low risk	On recruitment, midwife telephoned an independent clerk for allocation.
Blinding of participants and personnel (performance bias)   All outcomes	High risk	High risk of bias could have been introduced because women, carers and researcher could not be blind to group allocation after randomisation due to the nature of the intervention.
Blinding of outcome assessment (detection bias)   All outcomes	Unclear risk	No information provided
Incomplete outcome data (attrition bias)   All outcomes	High risk	Data analysed on ITT basis. Flow chart reports on participants from eligibility to completion. From randomisation similar numbers (water 58 (42%)/control 53 (39%)) became ineligible or did not use the allocated care option as might be expected in a study of this size which respected women's right to choice care options; however, this is a high percentage.
Selective reporting (reporting bias)	Low risk	All the data mentioned in the methods and that would reasonably be expected of this study are reported.
Other bias	Unclear risk	No mention of 1‐to‐1 care or not, but no other issue apparent.

Methods	Random assignment to water or traditional birth.
Participants	Primiparous, singleton fetus, cephalic presentation, term pregnancy (37‐42 weeks).
Interventions	Immersion in water during first and second stages of labour. 120 women. Traditional delivery group received, enema, shave, artificial rupture of membranes, fetal monitoring and parenteral nutrition, education on breathing and pushing. Water delivery group; enema and shower before 3 cm cervical dilation, vaginal examination to confirm dilation of 4 cm, entered water bath, maintained at 35‐37 degrees Celsius, free to adopt any position in water, fetus monitored every 15 minutes.
Outcomes	Pain intensity on scale 1‐3 Total duration of labour Blood loss in 24 hours Perineal condition Apgar score
Notes	No mention of 1:1 care Medical model of care evident No description of 'bath' size or shape but refers to free movement Undertaken in 1 unit in China Dates of trial: June 2012 ‐ July 2013 Funding: not reported Declaration of interest: the authors declare that there are no conflicts of interest
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No indication of how randomisation achieved
Allocation concealment (selection bias)	Unclear risk	No information about concealment
Blinding of participants and personnel (performance bias)   All outcomes	High risk	Not possible
Blinding of outcome assessment (detection bias)   All outcomes	Unclear risk	No information provided
Incomplete outcome data (attrition bias)   All outcomes	Low risk	All participants accounted for, no attrition
Selective reporting (reporting bias)	Unclear risk	Delivery data limited, but all intended outcomes reported on, but no differentiation by stages of labour
Other bias	Unclear risk	Medical module of care within study unit. No description of water bath intervention

Methods	Participants randomly allocated to water birth or conventional birth groups
Participants	200 pregnant women,100 allocated to water birth, 100 to conventional (land) birth
Interventions	Immersion in water during second stage of labour Women in water were able to move about freely but pool not described Conventional care conducted on bed, no further information about care provided
Outcomes	Duration of labour; mode of delivery, Apgar at 1and 5 mins. No raw data provided ‐ only P values for outcomes.
Notes	Mean duration of first stage P < 0.344. mean duration of second stage P = 0.372; mean duration of third stage P = 0.523. caesarean section rate significantly higher in land group P = 0.018. Apgar scores were significantly higher for water birth group at 1 min P = 0.026, at 5 mins P < 0.001. No difference found for other variables Omolbanin hospital, Mashhad, Iran Dates of trial: 2008 and 2009 Funding: not reported Declaration of interest: not reported
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Full paper in Iranian, so data based on English abstracts only, which did not provide this information
Allocation concealment (selection bias)	Unclear risk	Full paper in Iranian, so data based on English abstracts only, which did not provide this information
Blinding of participants and personnel (performance bias)   All outcomes	High risk	Blinding of participants and carers not possible due to nature of intervention
Blinding of outcome assessment (detection bias)   All outcomes	Unclear risk	No information provided
Incomplete outcome data (attrition bias)   All outcomes	High risk	Data implies attrition of 17 of 100 in the water group and 12 in the traditional care group but translation did not provide details
Selective reporting (reporting bias)	Unclear risk	Full paper in Iranian, so data based on English abstracts only, which did not provide this information
Other bias	Unclear risk	Full paper in Iranian, so data based on English abstracts only, which did not provide this information

Methods	Randomisation stated but only described as 'by lots'.  Methodological qualities: selection bias: no information; performance bias: high risk of bias could have been introduced because researcher could not be blind to group allocation after randomisation; exclusion bias: low risk of bias as no dropouts reported; bias conclusion: moderate bias. 1 or more criteria partially met. May raise some doubt about the results.
Participants	33 women, 18 water, 15 control In labour (cervix 4 cm dilated) Low risk ‐ term, 1 fetus, no complications in current or any previous pregnancy/birth
Interventions	Immersion in water during first stage of labour Intervention was use of bath for max of 60 minutes. Bath was thermally insulted, oval, size 150 cm by 110 cm, by 70 cm deep. Volume was 730 litres. Water temperature 37 degree Celsius No pharmacological analgesia available to either control or intervention group during study hour. After use of bath labour care as normal and could access 'usual' pain relief methods, positions. No mention of 1‐to‐1 care or not.
Outcomes	Duration of first and second stage of labour Pain relief used, pain score before and after study period (1 hour), own assessment in postnatal questionnaire on day 2 postpartum Blood loss, perineal trauma, Apgars Maternal pulse, temperature, blood pressure
Notes	Undertaken in Finland ‐ 1 hospital Dates of trial: April 1997 ‐ March 1998 Funding: not reported Declaration of interest: not reported
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomised 'by lots' in translation so very unclear what this means
Allocation concealment (selection bias)	Unclear risk	Described as randomised but translation does not indicate how concealed
Blinding of participants and personnel (performance bias)   All outcomes	High risk	High risk of bias could have been introduced because women, carers and researcher could not be blind to group allocation after randomisation due to the nature of the intervention
Blinding of outcome assessment (detection bias)   All outcomes	Unclear risk	No information provided
Incomplete outcome data (attrition bias)   All outcomes	Unclear risk	Not reported
Selective reporting (reporting bias)	Unclear risk	Unable to assess this from translation
Other bias	Unclear risk	Full translation not available, just extracts as requested on Cochrane Pregnancy and Childbirth Group translation sheet

Methods	Randomised when regular contractions and eligible.  Sealed opaque envelopes.  Methodological qualities: selection bias: low risk; adequate concealment at time of randomisation; performance bias: high risk of bias; could have been introduced because researcher could not be blind to group allocation after randomisation; exclusion bias: moderate risk of bias; 46 were excluded and 11.1% (KH) and 4.4% (LH) did not use tub; bias conclusion: moderate bias; 1 or more criteria partially met. May raise some doubt about the results.
Participants	Study group: KH: n = 364.  OH: n = 95; LH: n = 153; total = 612.  Control group: KH: n = 376; OH: n = 97; LH: n = 152; total = 625.  Inclusion criteria: gestation term defined as greater than 35 weeks; in active labour, defined as a cervical dilatation of 3 cm or more; ruptured membranes on entry also eligible; ambulation, analgesics and anaesthesia were allowed.
Interventions	Immersion in water during first stage of labour. Study group: warm bath; no information on management of care for either group;  no information on water temperature or bath size. Control group: shower allowed. Water use in first stage, no mention of 1‐to‐1 second care or not.
Outcomes	Maternal outcomes: use of analgesia/anaesthesia; mode of delivery; trauma to the birth canal requiring suturing. Neonatal outcomes:* neonatal condition; admittance to NICU or high dependency care unit. Additional outcomes: secondary arrest and delivered in OP position.
Notes	3 obstetric units in Sweden ‐ 1992‐1995 Funding: not reported Declaration of interest: not reported
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not indicated
Allocation concealment (selection bias)	Low risk	Sealed opaque envelopes
Blinding of participants and personnel (performance bias)   All outcomes	High risk	High risk of bias could have been introduced because women, carers and researcher could not be blind to group allocation after randomisation due to the nature of the intervention
Blinding of outcome assessment (detection bias)   All outcomes	Unclear risk	No information provided
Incomplete outcome data (attrition bias)   All outcomes	High risk	From a total of 1279 women, 42 were excluded across both groups and all centres for obstetric reasons
Selective reporting (reporting bias)	Low risk	All outcomes mentioned in methods are reported
Other bias	Unclear risk	Study was started in 1 unit then after 2 years 2 further obstetric units were involved to achieve the required sample size

Methods	Randomisation by consecutively numbered, computer‐generated random allocation in sealed opaque envelopes.  Methodological qualities: selection bias: low risk; adequate concealment at time of randomisation; performance bias: high risk of bias could have been introduced because researcher could not be blind to group allocation after randomisation; exclusion bias: high risk of bias; bias conclusion: high risk of bias. Where 1 or more criteria are not met may cause plausible bias that seriously weakens confidence in the results.
Participants	Academic hospital, Ontario, Canada.  Inclusion criteria: term pregnancy defined as gestation greater than 37 weeks; previous CS included (VBAC); in active labour defined as a cervical dilatation of 3 cm or more; ruptured membranes on entry also eligible; ambulation, analgesics and anaesthesia were allowed. 800 women were randomised, 15 were withdrawn 8 from study group and 7 from control group. Nearly half (46%) of the women in the study group did NOT use the bath but were still considered experimental participants with the ITT. 41 of the women did not meet eligibility criteria but were still included and results were analysed.  Study group: n = 393‐ stated but Experimental group adds up to 394. Control group: n = 392
Interventions	Immersion in water during first stage of labour. The use of a Parker whirlpool hot tub with jets during labour. Bath temperature between 38‐39 degrees celsius. Mean total time in tub was 54 minutes. No births in tub. No water immersion during labour. Refer to care being provided by assigned nurse, and all had be trained to care for women using immersion, but not clear if this is 1‐to‐1 second care. First stage only.
Outcomes	Maternal outcomes: use of analgesia/anaesthesia; augmentation of labour; presence of meconium‐stained liquor; duration of labour and birth; mode of delivery. Additional outcomes:* maternal age; gravida; cervical dilatation; duration in tub; VBAC.
Notes	Data table 1 incorrect. No response from authors Dates of trial: February‐September 1998 Funding: not reported Declaration of interest: not reported
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated
Allocation concealment (selection bias)	Low risk	Consecutively numbered sealed opaque envelopes
Blinding of participants and personnel (performance bias)   All outcomes	High risk	High risk of bias could have been introduced because women, carers and researcher could not be blind to group allocation after randomisation due to the nature of the intervention
Blinding of outcome assessment (detection bias)   All outcomes	Unclear risk	No information provided
Incomplete outcome data (attrition bias)   All outcomes	High risk	All participants are accounted for, and 15 withdraws were detailed, as were 41 who did not meet criteria but were recruited
Selective reporting (reporting bias)	Low risk	All outcomes mentioned in methods are reported, and seem appropriate for the study and topic
Other bias	Unclear risk	No information on this

Methods	Randomisation by packets containing random computer‐generated codes.  Methodological qualities: selection bias: high risk ‐ the researcher knew group allocation before obtaining informed consent; performance bias: high risk of bias could have been introduced because researcher could not be blind to group allocation after randomisation; exclusion bias: low risk of bias ‐ no exclusions. Main outcome not stated.  Determine safety and effect of water immersion on women in labour.  Most women stayed in the tub for 30‐45 minutes.  Bias conclusion: moderate bias. 1 or more criteria partially met. May raise some doubt about the results.
Participants	Study group: n = 45  Control group: n = 48  Inclusion criteria: gestation between 36‐41 weeks; no major obstetric or medical complication; active labour between 4‐7 cm cervical dilatation; intact membranes on entry; normal FHR patterns; ambulation and analgesics were allowed.
Interventions	Immersion in water during first stage of labour. Study group: the use of a hot tub with air jets and with a moulded seat during labour. Bath temperature between 32‐41 degrees Celsius.  Control group: no water immersion during labour. Showers were allowed. First stage of labour
Outcomes	Maternal outcomes: Maternal age; gestational age; ethnicity; parity; water temperature; duration in bath; use of analgesia; augmentation; cervical dilatation; duration of first stage of labour; duration of second stage of labour; duration of admission to delivery; duration of ruptured membranes; blood pressure; pulse; maternal temperature; method of delivery; Fetal outcomes:* FHR patterns; Apgar score at 1 minute; Apgar score at 5 minutes; neonatal weight;. Additional outcomes: *postnatal maternal infections; re‐admissions to hospital.
Notes	Academic hospital, Houston, Texas, USA. December 1990 to December 1991 Funding: not reported Declaration of interest: not reported
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated code
Allocation concealment (selection bias)	High risk	Midwife know the allocation at the time of recruitment, and risk of bias acknowledged but women apparently would not be recruited if they did not know which allocation they had
Blinding of participants and personnel (performance bias)   All outcomes	High risk	High risk of bias could have been introduced because women, carers and researcher could not be blind to group allocation after randomisation due to the nature of the intervention
Blinding of outcome assessment (detection bias)   All outcomes	Unclear risk	No information provided
Incomplete outcome data (attrition bias)   All outcomes	Low risk	All participants are accounted for throughout study with no withdrawals
Selective reporting (reporting bias)	Low risk	All outcomes mentioned in method are reported, and seem appropriate for the study and topic
Other bias	Unclear risk	There were significantly more primigravid women in water group, which could affect outcomes, and is a confounding variable

Methods	Randomisation into sequentially numbered sealed opaque envelopes containing the code. Prepared in variable random blocks stratified for parity.  Randomised when in active birth labour and met inclusion and exclusion criteria.  Methodological qualities: selection bias: none; performance bias: high risk of bias could have been introduced because researcher could not be blind to group allocation after randomisation; exclusion bias: low risk of bias all women received their allocated treatment. Analysed according to ITT. 1 lost to follow‐up; bias conclusion: moderate bias. 1 or more criteria partially met. May raise some doubt about the results.
Participants	Study group: n = 59  Control group: n = 61  Inclusion criteria: in active labour; primiparous women with cervical dilatation of 4 cm to 7 cm; multiparous women with cervical dilatation of 4 cm to 6 cm; low‐risk women; read/understand English. Exclusion criteria poor obstetric history; previous CS; medical disorders; pre‐eclampsia; multiple pregnancy; intrauterine growth impairment; < 36 weeks and > 42 weeks; pyrexia; meconium‐stained liquor; prolonged ruptured of membranes.
Interventions	Immersion in water during first stage of labour. Study group: labour in water; water temperature 34‐38 degrees Celsius; analgesia as required; exit for second stage; not out of the water for more than 30 minutes.  Control group: encouraged ambulation; if lie down use side analgesia as required.  Same midwife for all women (so 1‐to‐1 second stage care assumed) also same observer/assessor of pain for all. First stage study
Outcomes	Outcomes reported: Maternal outcomes: pain; use of analgesia/anaesthesia; augmentation of labour; blood pressure; pulse; duration of labour and birth; mode of delivery; trauma to the birth canal requiring suturing; blood loss; postpartum depression; breastfeeding; Fetal outcomes:* abnormal FHR patterns needing intervention. Additional outcomes:* studies which describe additional outcomes that may be of importance will be mentioned in the text; gestational age; maternal age; gravida; parity; cervical dilatation; duration in tub; meconium‐stained liquor.
Notes	Academic hospital, South Africa Dates of trial: not reported Funding: not reported Declaration of interest: not reported
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Random list compiled in different block size of 6 and 8 but not clear how this was achieved or by whom
Allocation concealment (selection bias)	Low risk	Sequentially‐numbered sealed opaque envelopes containing the allocation
Blinding of participants and personnel (performance bias)   All outcomes	High risk	High risk of bias could have been introduced because women, carers and researcher could not be blind to group allocation after randomisation due to the nature of the intervention
Blinding of outcome assessment (detection bias)   All outcomes	Unclear risk	No information provided
Incomplete outcome data (attrition bias)   All outcomes	Low risk	All participants are accounted for throughout study with no withdrawals
Selective reporting (reporting bias)	Low risk	All outcomes mentioned in method are reports, and seem appropriate for the study and topic
Other bias	Unclear risk	Researcher recruited and cared for all women and provided 1‐to‐1 care

Methods	Clinical trial with women equally divided into 2 groups. Information available understood to be random allocation.
Participants	Women 16‐28 years of age gravida 1 or 2 gestational age 38‐42 week
Interventions	Immersion in water during first and second stage of labour (100 women) Control group described as 'normal delivery' Active management of labour was undertaken, with use of oxytocin use for ineffective contractions or lack of cervical progress in 2 hours. Promethazine available analgesia with no indication if this resulted in exit from the pool, as the use of this drug would exclude water use in many locations. No indication of 1:1 care.
Outcomes	Duration of first stage of labour Duration of second stage of labour pain score percentage who used analgesia percentage who received oxytocin percentage who had episiotomy percentage who had normal birth percentage who had Apgar score lower than 8 percentage of Woman's satisfied with mode of delivery
Notes	Conducted in Asalian Gynaecological hospital in Iran. The full name of the lead author paper that was initially labelled as by author Akbari 2008 ‐ is Soheila Akbari Torkamani and has be renamed according. This is 1 trial with 2 publications. Dates of trial: February 2006 to February 2007 Funding: not reported Declaration of interest: not reported
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No information provided
Allocation concealment (selection bias)	Unclear risk	No information provided
Blinding of participants and personnel (performance bias)   All outcomes	High risk	High risk of bias because women and carers could not be blind to group allocation after randomisation due to the nature of the intervention
Blinding of outcome assessment (detection bias)   All outcomes	Unclear risk	No information provided
Incomplete outcome data (attrition bias)   All outcomes	High risk	No attrition data provided,however most of outcome data are provided as percentages (see above) and on trying to convert this data to numbers it is evident that data are missing, appears to have different data missing for different outcomes and therefore could not be converted to numbers for analysis
Selective reporting (reporting bias)	High risk	Women who required a caesarean section after apparently consenting and entering the trial were excluded indicating analysis was not by ITT. There are no data on the number of such women in each group
Other bias	Unclear risk	No information on type of pool used

Methods	Randomisation schedule provided by National Perinatal Epidemiology Unit, Oxford. A person unconnected to study prepared by consecutively numbered, computer‐generated random allocation in sealed opaque envelopes.  Methodological qualities: selection bias: low risk; adequate concealment at time of randomisation; performance bias: high risk of bias could have been introduced because researcher could not be blind to group allocation after randomisation; exclusion bias: moderate risk as, although expected and 2:1 randomisation undertaken, 16 of 40 women in water arm and 2 of 20 in control arm did not receive their allocated treatment. Analysed according to ITT. 1 woman withdrew; bias conclusion: moderate risk of bias. Where 1 or more criteria are not met may cause plausible bias that seriously weakens confidence in the results.
Participants	2 groups in RCT part of study. Water n = 40 Land n = 20 (2:1 ratio as about local experience was 50% of women choose not to use water). Women recruited through community midwife, posters in clinics, and media promotions and interested women contacted researcher or gave permission to own midwife to pass on information. Aged 18‐50 Low risk
Interventions	Immersion in water during first and second stages of labour. Results do not distinguish which of the women allocated to pool, did not use pool (16 of 40 women), used pool for first stage only (13 of 40 women), used pool in second stage but not for birth (1 woman), or gave birth in the pool (10 women) (no subgroup analysis). Data entered into both 'immersion in water versus no immersion during first stage of labour ' AND 'immersion in water versus no immersion during second stage of labour' DATA and ANALYSIS section. Waterbirth pool ‐ dimensions/volume not described, temperature described as recorded but data not provided. No mention of 1‐to‐1 care or not.
Outcomes	ITT analysis done. Maternal: age, social history, pulse, temperature, maternal satisfaction on scale of 0‐6 immediately post birth and in 6 week postal questionnaire. Labour: length of first, second stages; analgesia used; augmentation; mode of birth. Fetus/neonate: cord arterial and venous gases, Apgar score at 1, 5 and 10 mins, time to first respiration, rectal temperature at birth, ear swabs, method of feeding, date and time of first feed, admission to neonatal unit (plus any interventions needed) infection, any mortality/morbidity. Water; duration in water, water temperature, microbiological analysis at end of labour/use.
Notes	Non‐randomised, preference arm data not included although additional 20 participants in this part of study. 16 (40%) of water women did not use water. UK study. Dates of trial: not reported Funding: partly funded by Getting Started in Research Grant from Northampton General Hospital NHS Trust. Declaration of interest: not reported
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated independent of study
Allocation concealment (selection bias)	Low risk	Consecutively numbered in sealed opaque envelopes
Blinding of participants and personnel (performance bias)   All outcomes	High risk	High risk of bias could have been introduced because women, carers and researcher could not be blind to group allocation after randomisation due to the nature of the intervention
Blinding of outcome assessment (detection bias)   All outcomes	Unclear risk	No information provided
Incomplete outcome data (attrition bias)   All outcomes	High risk	All participants are accounted for throughout study with no withdrawals, however many did not receive the allocated intervention
Selective reporting (reporting bias)	Low risk	All outcomes mentioned in method are reported, and seem appropriate for the study and topic
Other bias	Unclear risk	40% or water group did not use water, which is consistent with choice and other papers on this topic

Study	Reason for exclusion
Bastide 1990	Unpublished data from 1990 available only. Intervention was whirlpool bath and was inadequate to confirm immersion of the pregnant abdomen was possible. We contacted the author for further information, but nothing was provided.
Benfield 2001	The intervention was not consistent with immersion of the pregnancy abdomen, as women were in a limited depth of water; were asked to adopt semi‐recumbent positions on a partially inflated air raft with attached head pillow (authors description) for 1 hour, and had cannulation to facilitate repeat blood samples. All of which limits mobility and is not consistent with water immersion in labour.
Cai 2005	Cases drawn from existing records, not randomised design.
Calvert 2000	The intervention was inappropriate as the study was to compare the effect of the essential oil of ginger compared to essential oil of lemon grass rather than water immersion.
Cluett 2001	Women had all been diagnosed as having dystocia in the first stage of labour (less than 1 cm/hr progress after established labour), and therefore at increased risk of complications and this does not meet participant inclusion criteria.
Cluett 2004	Women had all been diagnosed as having dystocia in the first stage of labour (less than 1 cm/hr progress after established labour), and therefore at increased risk of complications and this does not meet participant inclusion criteria.
Henrique 2015	The intervention is hot water spray, or shower, and not immersion in water and hence is not the intervention of this review.
Irion 2011	Antenatal women standing in water versus antenatal women sat in water with legs elevated and peripheral oedema assessed. Not immersion and not labour or birth.
Kashanian 2013	The participants are antenatal women, not in labour or during birth.
Khadijeh 2015	The intervention is warm water shower, and not immersion in water and hence is not the intervention of this review as the physiological impact of a shower is considered to be different to immersion.
Labrecque 1999	The Intervention does not meet the inclusion criteria for this review, as 3 interventions were compared (1) ISWs, (2) transcutaneous electrical nerve stimulation and (3) standard care that included back massage, and all has access to a whirlpool bath and liberal mobilisation, and therefore is not specifically about water immersion.
Lee 2013	The intervention is inappropriate being a 20‐minute shower, not immersion in water during first stage of labour.
Malarewicz 2005	Inadequate description of the pool to confirm immersion. The only outcome provided is cervical dilation between 2 time points, which is a subjective measurement by the caregiver, of a non linear outcome. No data were provided on length of labour, which is outcome used within this review. No other outcome was provided, despite direct request for non published data to authors.
Zou 2008	The design description indicated this as a cohort study not a randomised trial.

Trial name or title	Effect of water immersion during the first stage of labour on pain and the outcome of labour of primipara women attending to Khaleej‐e‐ fars hospital in Bandar Abbas
Methods	Clinical trial with 2 arms
Participants	Nulliparous women; age 35‐18 years; height over 150 cm; BMI 18.5‐24.9; singleton pregnancy; gestational age 37‐40; participation in preparation for childbirth classes; vertex presentation; alive fetus; not having risk factors (abnormal vital signs of mother‐ of mother underlying disease‐ prolonged rupture of membrane‐ vaginal bleeding, oligo‐ or polyhydramnios‐ placenta previa‐ placental abruption‐ meconium‐stained‐ intrauterine growth restriction‐ fetal macrosomia‐ abnormal fetus‐ history of infertility); regular uterine contractions; 4 cm cervical dilatation; Normal NST
Interventions	Immersion during the active phase of first stage of labour in a tub full of water at the appropriate temperature, for all of the first stage of labour
Outcomes	Labour pian intensity, duration of first stage of labour, duration of second stage of labour, perineal status, newborn Apgar score
Starting date	November 2015
Contact information	Fatemeh Dabiri, Shahid Beheshti University of Medical Sciences  Shahid Beheshti Nursing & Midwifery collage,Vali‐Asr Avenue,Cross of Vali Asr and Neiaiesh Highway, Tehran Iran, Islamic Republic of Iran
Notes	No outcome data published or provided at time of this review

PERMALINK

Immersion in water during labour and birth

Elizabeth R Cluett

Ethel Burns

Anna Cuthbert

Abstract

Background

Objectives

Search methods

Selection criteria

Data collection and analysis

Main results

Authors' conclusions

Plain language summary

Summary of findings

Background

A history of water immersion

Description of the condition

Description of the intervention

Water immersion during the first and second stage of labour

Third stage of labour

How the intervention might work

Why it is important to do this review

Objectives

Methods

Criteria for considering studies for this review

Types of studies

Types of participants

Types of interventions

Types of outcome measures

Primary outcomes

Maternal

Fetal/Neonatal

Secondary outcomes

Maternal

Fetal/Neonatal outcomes

Other

Caregiver outcomes

Search methods for identification of studies

Electronic searches

Searching other resources

Data collection and analysis

Selection of studies

Data extraction and management

Assessment of risk of bias in included studies

(1) Random sequence generation (checking for possible selection bias)

(2) Allocation concealment (checking for possible selection bias)

(3.1) Blinding of participants and personnel (checking for possible performance bias)

(3.2) Blinding of outcome assessment (checking for possible detection bias)

(4) Incomplete outcome data (checking for possible attrition bias due to the amount, nature and handling of incomplete outcome data)

(5) Selective reporting (checking for reporting bias)

(6) Other bias (checking for bias due to problems not covered by (1) to (5) above)

(7) Overall risk of bias

Assessment of the quality of the evidence using the GRADE approach

Measures of treatment effect

Dichotomous data

Continuous data

Unit of analysis issues

Cluster‐randomised trials

Dealing with missing data

Assessment of heterogeneity

Assessment of reporting biases

Data synthesis

Subgroup analysis and investigation of heterogeneity

Sensitivity analysis

Results

Description of studies

Results of the search

1.

Included studies

Design

Sample sizes

Setting and dates of trials

Participants

Interventions and comparisons

Outcomes

Funding sources

Declarations of interest

Excluded studies

Risk of bias in included studies