Abstract
Background
In labour, ketosis (the elevation of ketone bodies in the blood) is a common occurrence, due to increased physical stress, which is often compounded by reduced oral intake. The effect of ketosis on the mother and baby during labour is not clear, therefore, there is uncertainty as to whether ketosis is a normal physiological response or whether women with ketosis in labour require intervention (such as intravenous fluids or increased oral intake) for maternal and infant wellbeing. This uncertainty has resulted in differences in opinion and practice by those providing care for women in labour.
Objectives
To assess the effects on maternal, fetal and neonatal outcomes of intravenous fluids or increased oral intake administered to women in labour for the treatment of ketosis compared with no intervention (defined as no oral intake, ice chips only, or oral intake on demand) and to also assess the effects of different types of intravenous fluids administered.
Search methods
We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (January 2008), CENTRAL (The Cochrane Library 2007, Issue 2), MEDLINE (1950 to January 2007), EMBASE (1988 to January 2007) and CINAHL (1982 to 2007).
Selection criteria
All published and unpublished randomised trials in which additional oral intake or intravenous fluids, or both, were used for the treatment of women with ketosis in labour.
Data collection and analysis
Two authors independently assessed potentially eligible trials. The authors sought additional information on trial methods and outcome data to enable consideration of eligibility of studies. However, at the time of the review, no information was received.
Main results
We identified six trials as potentially eligible for inclusion in this review. All six studies were excluded. Therefore no trials are included in this review.
Authors' conclusions
There is no information on which to base practice in the treatment of women with ketosis during labour. Further research is required to identify more clearly the association between ketosis in labour and pregnancy outcome. Future trials should examine the effects of no interventions and different types of intravenous and oral fluids on these clinically important outcomes, and include women's perception and satisfaction with care during labour and birth.
Keywords: Female; Humans; Pregnancy; Labor, Obstetric; Fluid Therapy; Fluid Therapy/methods; Infusions, Intravenous; Ketosis; Ketosis/therapy
Plain language summary
Interventions for ketosis during labour
Physical stress compounded by reduced food intake during labour can lead to raised levels of ketones in the blood and urine (ketosis). Ketone bodies transport fat‐derived energy from the liver to other organs to provide an alternative source of energy. They also cross the placenta and the effect of ketosis on mother and baby is not clear. It is not clear whether ketosis during labour is a normal physiological response, or if women with ketosis in labour require intervention (such as intravenous and oral fluids). This uncertainty has resulted in differences in opinion and practice. Adverse effects of ketosis for the mother include increased likelihood of augmentation of labour, forceps‐assisted delivery and postpartum blood loss.
Yet intravenous therapies can have adverse effects, either by interfering with glucose and insulin levels for the mother and infant (causing neonatal hypoglycaemia) or lowering sodium level, for example. Other reported adverse effects include headache, nausea, maternal fluid overload, slowing of labour and difficulty in establishment of breastfeeding, as well as local pain and discomfort and interference with the woman's freedom of movement in labour. The newborn may have acidic blood and increased lactate levels.
This review found no information on which to base practice in the treatment of women with ketosis during labour. The authors looked for studies comparing oral intake or intravenous fluids with no intervention (defined as no oral intake, ice chips only or oral intake on demand) and pregnancy outcomes.
The only six studies identified focussed on maternal biochemical measures during or shortly after labour and could not be included in the review. The studies were conducted in the late 1970s to mid‐1980s. Future trials should examine the use of different types of intravenous and oral fluids on clinically important outcomes and include women's perception and satisfaction with care during labour and birth.
Background
Under normal conditions the body utilises glycogen, which is stored in the liver, for energy. When glycogen stores are depleted, the liver metabolises fat, giving rise to ketone bodies. Ketone bodies are molecules which transport fat‐derived energy from the liver to other organs and are normally oxidised to carbon dioxide, water and usable energy by peripheral tissue. However, when placed under more severe conditions, for example, starvation and excessive exercise, peripheral metabolic processes cannot cope and ketones accumulate in the blood. This state is known as ketosis and usually becomes evident by the presence of ketone bodies in the urine (ketonuria). When ketosis occurs, the body also utilises ketone bodies as readily available alternative energy. Therefore, under normal circumstances, ketonuria is thought to indicate the success of the body's physiologically protective response of using alternative energy sources in times of increased energy requirements and indicates a need for increased caloric intake (Anderson 1998; Kubli 2002).
The gradual fall in glucose levels and increase in free fatty acids occurring in pregnancy results in an increased likelihood of ketosis (Anderson 1998). In labour, ketosis is a common occurrence, due to the increased physical stress and often compounded by reduced oral intake (Dumoulin 1984; Goer 1995). Although desire for food naturally tapers off during labour (Ludka 1993), routine policies in many maternity units of withholding or restricting oral intake in labour is thought to make a significant contribution to the increased risk of ketosis. This practice was first introduced in the late 1940s to reduce the risk of anaesthetic related complications (Broach 1988) and its role in the care of women in labour in modern care settings has been questioned (Anderson 1998; Goer 1995). The effect of restricting oral food and fluid during labour is beyond the scope of this review but is the focus of another Cochrane review (Singata 2002).
The clinical importance of detecting ketosis in labour is not clear. Many believe that it represents a normal physiological response without adverse effects to the woman or baby (Keppler 1988; Sommer 2000). The association between marked ketonuria and prolonged labour is well known. However, which is the cause and which is the effect remains unclear (Dumoulin 1984; Hazle 1986). A higher incidence of ketosis has also been described for nulliparous women (Broach 1988; Foulkes 1985). Adverse effects include increased likelihood of augmentation of labour, forceps‐assisted delivery and postpartum blood loss (Broach 1988; Foulkes 1985). Although ketones do cross the placenta, effects on the fetus are unknown (Foulkes 1985). However, reduced glucose levels in the mother have been shown to affect fetal breathing and general fetal activity (Ludka 1993).
Ketonuria is usually detected by a simple bedside urine test using firm plastic strips to which are affixed reagent areas (Ketostix/Multistix) (Dumoulin 1984; Ludka 1993). However, a high false positive rate has been reported which may increase the risk of unnecessary intervention (Anderson 1998; Ludka 1993).
While the presence of ketonuria for well women is now generally accepted as a normal physiological response to labour which is often managed conservatively, variation in practice exists. Management strategies may include administration of intravenous fluids; encouraging oral intake of food and fluids (including high calorie preparations), and no intervention. This lack of consistency reflects the lack of reliable evidence for management strategies combined with limited understanding of the normal biochemistry of labouring women (Goer 1995).
Adverse effects of additional oral intake during labour include nausea and vomiting in labour and the immediate postpartum period (Kubli 2002) and, although extremely rare, aspiration of gastric contents when general anaesthesia is used (Mendelson's Syndrome) (Scheepers 2002).
The most commonly used intravenous therapy solutions are crystalloid based fluids of dextrose/glucose, normal saline and balanced salt solutions or Hartmann's (compound sodium lactate) (Johnson 1989; Wasserstrum 1992). The use of intravenous therapy for women in labour is however, not without adverse effects. The use of large quantities and volumes of intravenous glucose (greater than 25 g glucose) in labouring women can lead to maternal hyperglycaemia and iatrogenic hyperinsulinism in the fetus, as well as subsequent postnatal hypoglycaemia and jaundice (Dumoulin 1984; Foulkes 1985; Hazle 1986; Johnson 1989). Another potential hazard of excessive administration of salt‐free intravenous solutions in labour is acute dilutional hyponatraemia in both the mother and neonate (Dumoulin 1984; Keppler 1988; Wasserstrum 1992). Other reported adverse effects include decreased fetal blood pH and increased fetal lactate, headache, nausea, maternal fluid overload, slowing of labour and difficulty in establishment of breastfeeding (Foulkes 1985; McKay 1988). The use of intravenous therapy may also result in local pain and discomfort and reduces the woman's freedom of movement in labour (Broach 1988).
This review will address the risks and benefits of treatment of women with ketosis in labour.
Objectives
The primary objectives of the review are: (1) to assess the effects on maternal, fetal and neonatal outcomes of intravenous fluids with or without additional oral intake (fluids and food) administered to women in labour for the treatment of ketosis compared with no intervention (defined as no oral intake, ice chips only or oral intake on demand); (2) to assess the effects on maternal, fetal and neonatal outcomes of additional oral intake alone (fluids and food) for women in labour in the treatment of ketosis compared with no intervention (defined as no oral intake, ice chips only or oral intake on demand); (3) to assess the effects on maternal, fetal and neonatal outcomes of different types of intravenous fluids with or without additional oral intake (fluids and food) administered to women in labour for the treatment of ketosis.
A secondary objective of the review is to determine whether the effects on the primary outcome measures of spontaneous vaginal delivery, maternal satisfaction with labour care, maternal adverse effects and neonatal admission to intensive care nursery measures are influenced by different types of oral and intravenous fluids as follows: (i) intravenous therapy solutions, i.e. glucose solutions, balanced salt solutions (i.e. Hartmann), normal saline; (ii) high carbohydrate oral fluids.
Methods
Criteria for considering studies for this review
Types of studies
All published and unpublished randomised trials in which oral intake or intravenous fluids, or both, were used for the treatment of women with ketosis in labour.
Types of participants
Women with an uncomplicated pregnancy in labour and assessed as having ketosis defined as the presence of ketones in urine (ketonuria).
Types of interventions
Intravenous fluids or oral food and/or fluids administered for the treatment of women with ketosis in labour compared with no intervention (defined as no oral intake, ice chips only or oral intake on demand).
Types of outcome measures
Primary outcomes Spontaneous vaginal delivery Maternal satisfaction with labour care Maternal adverse effects ‐ vomiting, nausea, headache Neonatal admission to intensive care nursery
Secondary outcomes Maternal Augmentation with oxytocin Narcotic analgesia Epidural analgesia Intrapartum non‐reassuring fetal status Duration of labour Caesarean section Operative vaginal delivery Manual removal of placenta Primary or secondary postpartum haemorrhage Blood transfusion Pulmonary oedema Hyponatraemia Admission to intensive care unit Length of hospital stay Maternal aspiration syndrome (Mendelson's Syndrome)
Fetal and neonatal Cord blood pH less than 7.2 Apgar score less than seven at five minutes Admission to neonatal special care or intensive care nursery Neonatal hypoglycaemia Neonatal hyponatraemia Neonatal jaundice requiring phototherapy Use of intravenous therapy Use of gavage feeding Use of complementary feeding Breastfeeding at time of discharge Length of hospital stay Perinatal death
Search methods for identification of studies
Electronic searches
We searched the Cochrane Pregnancy and Childbirth Group’s Trials Register by contacting the Trials Search Co‐ordinator (January 2008).
The Cochrane Pregnancy and Childbirth Group’s Trials Register is maintained by the Trials Search Co‐ordinator and contains trials identified from:
quarterly searches of the Cochrane Central Register of Controlled Trials (CENTRAL);
weekly searches of MEDLINE;
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.
Details of the search strategies for CENTRAL and MEDLINE, the list of handsearched journals and conference proceedings, and the list of journals reviewed via the current awareness service can be found in the ‘Specialized Register’ section within the editorial information about the Cochrane Pregnancy and Childbirth Group.
Trials identified through the searching activities described above are each assigned to a review topic (or topics). The Trials Search Co‐ordinator searches the register for each review using the topic list rather than keywords.
Data collection and analysis
Standard methods of The Cochrane Collaboration and the Cochrane Pregnancy and Childbirth Group were used as described in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2006). The review authors worked independently in undertaking the assessment of potentially eligible trials for inclusion. Authors of four studies were contacted for additional information on methods and outcome data to enable assessment of eligibility for inclusion (Ames 1975; Inman 1971; Lawrence 1982; Morton 1985). However, at the time of this review, no information was received. Therefore, no studies are included in this review.
If we identify studies for inclusion in the future, we will use the following methods.
Selection of studies We will assess for inclusion all potential studies we identify as a result of the search strategy. We will resolve any disagreement through discussion or, if required, consult an outside person. Assessment of methodological quality of included studies We will assess the validity of each study using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2006). We will describe methods used for generation of the randomisation sequence for each trial.
(1) Selection bias (allocation concealment) We will assign a quality score for each trial, using the following criteria: (A) adequate concealment of allocation: such as telephone randomisation, consecutively numbered sealed opaque envelopes; (B) unclear whether adequate concealment of allocation: such as list or table used, sealed envelopes, or study does not report any concealment approach; (C) inadequate concealment of allocation: such as open list of random‐number tables, use of case record numbers, dates of birth or days of the week.
(2) Attrition bias (loss of participants, e.g. withdrawals, dropouts, protocol deviations) We will assess completeness to follow up using the following criteria: (A) less than 5% loss of participants; (B) 5% to 9.9% loss of participants; (C) 10% to 19.9% loss of participants; (D) more than 20% loss of participants. (3) Performance bias (blinding of participants, researchers and outcome assessment) We will assess blinding using the following criteria: (A) blinding of participants (yes/no/unclear); (B) blinding of caregiver (yes/no/unclear); (C) blinding of outcome assessment (yes/no/unclear).
Data extraction and management We will design a form to extract data. At least two review authors will extract the data using the agreed form. We will resolve discrepancies through discussion. We will use the Review Manager software (RevMan 2003) to double enter all the data or a sub‐sample.
When information regarding any of the above is unclear, we will attempt to contact authors of the original reports to provide further details.
Measures of treatment effect We will carry out statistical analysis using the Review Manager software (RevMan 2003). We will use fixed‐effect meta‐analysis for combining data in the absence of significant heterogeneity if trials are sufficiently similar.
Dichotomous data For dichotomous data, we will present results as summary relative risk with 95% confidence intervals. Continuous data For continuous data, we will use the weighted mean difference if outcomes are measured in the same way between trials. We will use the standardised mean difference to combine trials that measure the same outcome, but use different methods. If there is evidence of skewness, this will be reported.
Available case analysis We will analyse data on all participants with available data in the group to which they are allocated, regardless of whether or not they received the allocated intervention. If in the original reports participants are not analysed in the group to which they were randomised, and there is sufficient information in the trial report, we will attempt to restore them to the correct group.
Assessment of heterogeneity We will apply tests of heterogeneity between trials, if appropriate, using the I² statistic. If we identify high levels of heterogeneity among the trials, (exceeding 50%), we will explore it by prespecified subgroup analysis and perform sensitivity analysis. A random‐effects meta‐analysis will be used as an overall summary if this is considered appropriate.
Subgroup analyses We will conduct planned subgroup analyses classifying whole trials by interaction tests as described by Deeks 2001.
We plan to carry out subgroup analyses according to different types of oral and intravenous solutions as follows: (i) intravenous therapy solutions i.e: glucose solutions; balanced salt solutions i.e Hartmanns; normal saline. (ii) high carbohydrate oral fluids.
Results
Description of studies
We identified six studies (Ames 1975; Clark 1971; Inman 1971; Lawrence 1982; Menigaux 1993; Morton 1985) as potentially eligible for inclusion in this review. Following assessment, we excluded all six. One study (Clark 1971) was excluded as intravenous sodium bicarbonate was used as the intervention and another (Menigaux 1993) as women did not have ketosis on enrolment into the study. The remaining four studies (Ames 1975; Inman 1971; Lawrence 1982; Morton 1985) were excluded due to inadequate reporting of the outcome measures prespecified for this review. Therefore, no studies are included in this review.
Risk of bias in included studies
No studies were found meeting the criteria for inclusion in this review.
Effects of interventions
No studies were found meeting the criteria for inclusion in this review.
Discussion
The purpose of this review was to assess the risks and benefits of additional oral intake or intravenous fluids, or both, given to women for the treatment of ketosis during labour. We identified four small studies involving 168 women (Ames 1975; Inman 1971; Lawrence 1982; Morton 1985) as potentially eligible for inclusion in this review. However, we were unable to include any of these studies due to inadequate reporting of the outcome measures prespecified for this review. Although we have requested additional information from authors, at the time of this review we have received no responses. As these studies were conducted some time ago (late 1970s to mid‐1980s) it is unlikely that the required additional information will be forthcoming.
All four studies identified as potentially eligible for the review tested the effect of intravenous fluids given to women diagnosed with ketosis in the first stage of labour. All studies compared a range of substrates. Outcome measures focussed on maternal biochemical measures during or shortly after labour and birth. Clinically meaningful outcomes for mother and infant were not reported. However, from the limited available data from these studies, it would appear that the use of hypertonic solutions (e.g. 5%, 10% and 50% glucose and Hartmann's solution) has short‐term adverse effects on the maternal and fetal biochemical markers when compared with normal saline alone. Investigators reported increased incidence of lactic acidosis and maternal hyperglycaemia associated with such solutions. The effect of intravenous therapy on clinically important outcomes (such as fetal distress and neonatal hypoglycaemia) cannot be assessed based on the available information. No trials were identified which addressed the effect of additional oral fluids for women with ketosis in labour, compared with oral intake on demand or no intake or ice chips only.
The clinical importance of detecting ketosis and treating women with ketosis in labour is not clear. Under normal circumstances, ketonuria is thought to indicate a normal physiological response to episodes of increased energy requirements and indicates a need for increased caloric intake. In labour, ketosis is not an uncommon occurrence due to the increased physical stress which is often compounded by reduced oral intake. A reduction in oral intake may be driven by the woman herself (desire for food naturally tapering off), or routine policies in many maternity units of withholding or restricting oral intake in labour, or both. The practice of withholding food and fluids was first introduced in the late 1940s to reduce the risk of anaesthetic related complications, and its role in the care of women in labour in modern care settings has been questioned. Further research is required to more clearly identify the association between ketosis in labour and adverse pregnancy outcome.
Authors' conclusions
Implications for practice.
This review does not provide information to guide practice in the treatment of women with ketosis in labour.
Implications for research.
Further research is required to assess the association of ketonuria and adverse outcomes, such as length of labour, operative vaginal delivery rates, caesarean section rates, postpartum haemorrhage and neonatal outcomes. Future trials should examine the use of different types of intravenous and oral fluids on clinically important outcomes, and include women's perception and satisfaction with care during labour and birth.
What's new
| Date | Event | Description |
|---|---|---|
| 18 January 2012 | Amended | Contact details updated. |
History
Protocol first published: Issue 2, 2003 Review first published: Issue 3, 2008
| Date | Event | Description |
|---|---|---|
| 18 March 2008 | Amended | Converted to new review format |
Acknowledgements
We would like to thank Dr Ian Stephens (anaesthetist, Mater Mothers' Hospital, Brisbane, Queensland) for advice in the preparation of this review. We thank Karen New for her assistance with final editing of the review and for coordination of the review team in the final editing of the review. We thank Sharon Egan for reference management and copy editing.
As part of the pre‐publication editorial process, this review has been commented on by three peers (an editor and two referees who are external to the editorial team), a member of the Pregnancy and Childbirth Group's international panel of consumers and the Group's Statistical Adviser.
Characteristics of studies
Characteristics of excluded studies [ordered by study ID]
| Study | Reason for exclusion |
|---|---|
| Ames 1975 | Unclear data reported in relation to population, methodology and outcomes. |
| Clark 1971 | Type of intervention: intravenous sodium bicarbonate was used. |
| Inman 1971 | Excluded as different intravenous fluids were compared including sodium bicarbonate and aminosol vitrum therefore not meeting types of intervention criteria. No outcomes of interest reported. |
| Lawrence 1982 | No outcomes of interest reported. |
| Menigaux 1993 | Population: women did not have ketosis at the time of enrolment. |
| Morton 1985 | No outcomes of interest reported. |
Contributions of authors
All review authors contributed equally to the development of the protocol. Jocelyn Toohill and Vicki Flenady compiled the review. Vicki Flenady and Barbara Soong participated in final editing of the review.
Sources of support
Internal sources
Gold Coast Hospital, Southport, Queensland, Australia.
Centre for Clinical Studies, Mater Mothers' Hospital, South Brisbane, Queensland, Australia.
Mater Research Support Centre, Mater Health Services, South Brisbane, Queensland, Australia.
External sources
No sources of support supplied
Declarations of interest
None known.
Edited (no change to conclusions)
References
References to studies excluded from this review
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