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. 2024 Jul 23;19(7):e0298852. doi: 10.1371/journal.pone.0298852

Impact of continuous labor companion- who is the best: A systematic review and meta-analysis of randomized controlled trials

D M C S Jayasundara 1,2,*, I A Jayawardane 1,2,#, S D S Weliange 3,#, T D K M Jayasingha 1,#, T M S S B Madugalle 4,#
Editor: Tanya Doherty5
PMCID: PMC11265680  PMID: 39042637

Abstract

Background

Continuous labor support is widely acknowledged for potentially enhancing maternal and neonatal outcomes, the physiological labor process, and maternal satisfaction with the labor experience. However, the existing literature lacks a comprehensive analysis of the optimal characteristics of labor companions, particularly in comparing the effects of trained versus untrained and familiar versus unfamiliar labor companions across diverse geographical regions, both pre-and post-millennial. This meta-analysis addresses these research gaps by providing insights into the most influential aspects of continuous labor support.

Methodology

A thorough search of PubMed, Google Scholar, Science Direct, International Clinical Trials Registry Platform (ICTRP), ClinicalTrials.gov, Research4Life, and Cochrane Library was conducted from 25/06/2023 to 04/07/2023. Study selection utilized the semi-automated tool Rayyan. The original version of the Cochrane Risk of Bias tool was used to assess the quality of Randomized Controlled Trials (RCTs) while funnel plots gauged the publication bias. Statistical analysis employed RevMan 5.4, using Mantel-Haenszel statistics and random effects models to calculate risk ratios with 95% confidence intervals. Subgroup analyses were performed for different characteristics, including familiarity, training, temporal associations, and geographical locations. The study was registered in INPLASY (Registration number: INPLASY202410003).

Results

Thirty-five RCTs were identified from 5,346 studies. The meta-analysis highlighted significant positive effects of continuous labor support across various outcomes. The highest overall effect without subgroup divisions was the improvement reported in the 5-minute Apgar score < 7, with an effect size of 1.52 (95% Confidence Interval (CI) 1.05, 2.20). Familiar labor companions were better at reducing tocophobia, with an effect size of 1.73 (95% CI 1.49, 2.42), compared to unfamiliar companions, with an effect size of 1.34 (95% CI 1.14, 1.58). Untrained labor companions were the better choice in reducing tocophobia and the cesarean section rate compared to trained companions. For the analysis of tocophobia, the pooled effect sizes were 1.34 (95% CI 1.14, 1.57) and 1.84(95% CI 1.60, 2.12) in trained versus untrained subgroup comparisons. For the cesarean rate, they were represented as 1.22 (95% CI 1.05, 1.42) and 2.16 (95% CI 1.37, 3.40), respectively. The pooled effect size for the duration of labor was 0.16 (95% CI 0.06, 0.26) for the subgroup of RCTs conducted before 2000 and 0.53 (95% CI 0.30, 0.77) for the subgroup of RCTs conducted after 2000. A significant subgroup difference (<0.1) was found in relation to the duration of labor, cesarean section rate, oxytocin for labor induction, analgesic usage, and tocophobia in the subgroup analysis of geographical regions.

Discussion and conclusion

The beneficial effects of a labor companion are well-established in the literature. However, studies systematically assessing the characteristics of labor companions for optimal beneficial effects are lacking. The current study provides insights into the familiarity, training, temporal association, and geographical settings of labor companions, highlighting the differing impact of these characteristics on measured outcomes by evaluating the current randomized controlled trials on the topic. There is insufficient evidence to define the ’best labor companion’ owing to the heterogeneity of labor companions and outcome assessment across different studies. We encourage well-designed further research to fill the research gap.

Introduction

Background

The emotional process of labor and childbirth is often a fearful and stressful event for a pregnant mother [1]. The term ’tocophobia,’ originating from the Greek ’tokos’ (childbirth) and ’phabos’ (fear and anxiety), is an extreme anxiety or fear of childbirth [2]. In most cultures, the tradition of supporting a woman in labor is a community event with multiple participants other than the designated healthcare provider. The fear and anxiety of childbirth are augmented by an unfamiliar hospital environment, medical jargon, procedures, interventions, and transient separation from the family during labor [3]. The woman feels a sense of loss of control, isolation, and fear, peaking the level of anxiety [3]. To cope with this tocophobia, pregnant women sometimes choose cesarean section over natural birth [4]. Increased anxiety makes the woman more vulnerable to increased pain perception, prolonging the duration of labor and contributing to dystocia [5]. The pain and anxiety during labor increase the endogenous catecholamine release, causing ineffective uterine contractions and decreased placental blood flow [6]. An inefficient labor process may cause fetal and maternal complications, including the risk of fetal or neonatal hypoxia and death, infection, physical damage in the newborn, postpartum hemorrhage, maternal infection, and psychological distress due to anxiety, lack of sleep, and fatigue [5].

Strategies to alleviate tocophobia

Different clinical settings have adopted strategies to alleviate tocophobia, facilitating a smooth labor process. Support methods include having an accompanying companion for continuous labor support, induced sleep, hydrotherapy, and the Lamaze relaxation method [7]. The labor companion can be a non-caregiving nurse, midwife, friend, relative, family member, husband, or a person trained in supporting labor (doula) [4]. WHO defines labor support as the supportive care provided to women during labor, including emotional support, physical comfort, advice, and information giving [6]. WHO also recommends that a parturient should have a birth companion of her choice. However, it is not practiced in many lower-middle-income counties (LMIC) [8].

Beneficial effects of a labor companion

A companion for continuous labor support facilitates a smooth labor process, improving the maternal psychological status and fetal/neonatal well-being. Reported advantages include an increase in spontaneous vaginal births, reduced demand for analgesics, reduced need for oxytocin for labor augmentation, shorter duration of labor, decreased need for cesarean sections, minimal perineal trauma, and reduced requirement for instrumentation during labor, facilitating a smooth labor process [9–12]. Maternal psychological well-being is improved by lowering tocophobia, reduced postpartum depression and anxiety, and improved self-esteem and satisfaction measured postpartum [3, 13, 14]. Fetal/neonatal well-being is enhanced by the early establishment of exclusive breastfeeding, early skin-to-skin contact, and reduced need for neonatal resuscitation and neonatal hospital stay [15, 16].

Gap of knowledge

The quality of labor support and its beneficial outcomes depend on the type of companion used [17]. The labor companion can be trained or untrained and familiar or unfamiliar to the parturient. The evidence regarding the "best labor companion" is controversial, and studies do not show a clear consensus.

The rates of severe tocophobia, measured similarly, vary in different countries, and the reasons are unknown [18]. The prevalence of tocophobia was lower in the early years (1980s, 1990s) compared to more recent years (2000 onwards) [19]. The beneficial effects of a labor companion can be more pronounced in some countries than others and may have changed over time.

Objectives

The present meta-analysis aims to describe the characteristics of the most effective labor companion, highlighting the differences in beneficial effects of having a labor companion among different geographical regions and timelines.

Materials and methods

Search strategy

PubMed, Science Direct, Cochrane Library, Google Scholar, ClinicalTrials.gov, and International Clinical Trials Registry Platform (ICTRP) were searched from 25/06/2023 to 04/07/2023. To identify relevant studies, a set search strings such as "Labor companion," "Birth partner," "Doula," "Labor support person," "Childbirth coach," "Labor assistant," "Labor coach," "Birth attendant," "Labor caregiver," "Maternity support person," "Childbirth companion," "Labor ally," "Labor chaperone," "Pregnancy outcome," "Obstetric outcome," "Delivery outcome," "Birth outcome," "Fetal outcome," "Newborn outcome," "Infant outcome," "Neonatal outcome", and "Baby’s outcome" were employed, with Boolean expressions "AND" and "OR" used appropriately to construct precise search queries. Initially, the literature search was conducted without filters. Then, the results were refined using advanced search options like full-text articles and randomized controlled trials.

A manual search strategy was also applied to ensure inclusivity, focusing on identifying any missing studies by reviewing the most cited ten meta-analyses within the same databases.

Screening eligible studies

The study selection process was carried out meticulously in two rounds using a semi-automated tool, Rayyan [20], with one author as the reviewer (DMCSJ) and another as a collaborator (TDKMJ), employing a blind approach. In the first round, titles and abstracts were screened, eliminating duplicates and ineligible entries, with conflicts resolved by the reviewer (IAJ). The second round involved a similar blind approach for full-text screening, again with conflicts resolved by the reviewer (IAJ). The authors were contacted if additional information was required. The study selection process was transparently reported using the PRISMA 2020 flow diagram for updated systematic reviews [21].

A detailed search strategy is given as a separate file under supporting information (S10 File). A protocol exists for the current study, and a copy of the protocol is given as supporting information (S11 File).

Inclusion and exclusion criteria

Randomized controlled trials (RCTs) with full-text articles reporting results related to low-risk women with viable singleton pregnancies in cephalic presentation, admitted during the latent phase (cervical dilation 3–4 cm) with no contraindications for vaginal delivery were included in the study. RCTs in English language only were included. Studies reporting women with medical or psychiatric diseases, previous cesarean section, pelvic abnormalities not favoring vaginal birth, fetal distress, and any fetal anomaly were excluded. Any study designs other than RCT, including quasi-experimental trials, were excluded.

Data extraction

Key study characteristics were extracted and organized into predefined tables for outcome measures concerning facilitating the labor process, maternal psychological well-being, and fetal well-being. To ensure the integrity of the research, a second author independently reviewed the entire process, minimizing the potential for bias.

Risk of bias and quality assessment

The quality of each RCT was assessed using the original version of the Cochrane Risk of Bias tool [22]. Random sequence generation, allocation concealment, performance bias, detection bias, attrition bias, reporting bias, and other biases are used as criteria in the original version of the Cochrane Risk of Bias tool. Funnel plots were employed to gauge publication bias, with any deviation from the expected funnel-shaped distribution as an indicator of potential publication bias.

Primary outcomes

Primary outcome measures were the overall effectiveness of a labor companion regarding spontaneous vaginal delivery, analgesic usage, oxytocin for labor induction, duration of labor, in labor cesarean section, instrumental vaginal delivery, 5-min Apgar score, and tocophobia, without subgroup divisions.

Secondary outcomes

Secondary outcomes compared the effects of trained versus untrained labor companions, familiar versus unfamiliar labor companions, studies before versus after 2000, and studies in different geographical locations by introducing subgroups.

Description of subgroups

Subgroups were trained versus untrained labor companions, familiar versus unfamiliar labor companions, studies before versus after 2000, and studies in different geographical locations. Trained labor companions had one or more training sessions for the role of a labor companion before childbirth. In contrast, untrained labor companion directly attended childbirth without prior training about their expected role. A familiar labor companion was chosen by laboring women, usually a family member, friend, relative, or partner. In contrast, the healthcare facility introduced an unfamiliar labor companion, usually a community member or staff. Geographical locations were divided on a continental basis [23].

Statistical analysis

We used RevMan version 5.4 to analyze the following outcome measures reported by more than ten RCTs—spontaneous vaginal birth, tocophobia, use of analgesics, need for synthetic oxytocin, duration of labor, CS rate, instrumental vaginal delivery, and 5-min Apgar score. The Mantel-Haenszel statistical method, random effects analysis model, and risk ratio with a 95% confidence interval (CI) as effect measures were used for dichotomous data. For the continuous data inverse variance statistical method, the random effects analysis model and standard mean difference as effect measures were used. We assessed heterogeneity with the I2 statistic, considering p value < 0.1 or I2 > 50% indicators of significant heterogeneity. Subgroup analyses compared the effects of trained versus untrained labor companions, familiar versus unfamiliar labor companions, studies before versus after 2000, and studies in different geographical locations.

Results

Search results, study characteristics, and quality assessment

Fig 1 shows the PRISMA 2020 flow diagram for study selection. We identified 5346 studies from 7 databases and a manual search. After considering exclusion and inclusion criteria, 35 studies were selected for analysis.

Fig 1. PRISMA 2020 flow diagram for study selection after initial filtering.

Fig 1

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Table 1 summarizes the key characteristics of 35 RCTs, including the year of the study, country, number of participants, a description of the type of labor companion, and outcome measures. Studies span from 1986 to 2022 from various geographical regions: Asia, Africa, Europe, North America, South America and Australia. Three studies (8.57%) have less than 100 participants, while 7 (20%) have more than 500 participants. Hodnett (2002) from the USA had the highest number of participants, at 6915. Different studies have used labor companions with varying characteristics, such as familiar, unfamiliar, trained, and untrained. Twenty-three studies (65.71%) used trained labor companions, while 20 (57.14%) used unfamiliar ones. The individual studies have examined different outcome measures, with a recent emphasis on maternal psychological well-being.

Table 1. Key characteristics of randomized controlled trials analyzed in the meta-analysis.

Study Year Country Participants Labor companion Primary outcomes compared to the control group
Akbarzadeh [24] 2014 Iran 100 Researcher as doula Increased maternal satisfaction, Reduced fetal distress
Bello [17] 2009 Nigeria 585 Untrained familiar companion Reduction in CS, pain scores, and duration of labor. Improved maternal satisfaction.
Bolbol [5] 2016 Iran 100 Unfamiliar midwifery students Improved 5-min Apgar score, Reduced Duration of labor.
Breat [25] 1992 Belgium 262 Unfamiliar midwives Reduction in operative vaginal deliveries
Breat [25] 1992 France 1319 Unfamiliar midwives Reduction in operative vaginal deliveries
Breat [25] 1992 Greece 545 Unfamiliar midwives No difference in operative vaginal deliveries
Bruggemann [9] 2007 Brazil 212 Untrained familiar companion Decreased incidence of meconium-stained amniotic fluid. Improved maternal satisfaction.
Campbell [26] 2007 USA 494 Trained familiar community doula Improved maternal satisfaction and self-esteem.
Campbell [10] 2006 USA 586 Trained familiar community doula Decreased duration of labor, Improved 5-min Apgar score, No difference in intrapartum analgesic usage and CS.
Cogan [27] 1988 USA 25 Trained unfamiliar community doula Shorter duration of labor, Reduced need for intrapartum analgesia, Improved neonatal well-being.
Dickinson [28] 2002 Australia 992 Unfamiliar midwives Maternal satisfaction with epidural analgesia was higher compared to techniques like continuous labor companion.
Erica [16] 2022 Sweden 143 Trained familiar community doula No difference in the rating of labor care and emotional well-being.
Gagnon [29] 1997 Canada 100 Unfamiliar nursing officers Reduction in CS
Hemminki a [30] 1990 Finland 122 Unfamiliar midwifery students Increased maternal satisfaction, progress in labor and interventions, and mother and infant health were similar in the two groups.
Hemminki b [30] 1990 Finland 118 Unfamiliar midwifery students Increased maternal satisfaction, progress in labor and interventions, and mother and infant health were similar in the two groups.
Hodnett [31] 1989 Canada 103 Trained familiar birth attendants Less intrapartum analgesia, No difference in Duration of labor and CS, Increased use of Oxytocin
Hodnett [11] 2002 USA 6915 Unfamiliar nursing officers No difference in CS, maternal or neonatal events during labor, and hospital stay.
Hofmeyr [32] 1991 South Africa 189 Untrained, unfamiliar community doula Lower pain and anxiety scores, No measurable effect on the progress of labor
Isbir [13] 2015 Turkey 72 Unfamiliar midwifery students Less fear during delivery, lower pain scores, and shorter delivery period. No difference in oxytocin use.
Kashanian [33] 2010 Iran 100 Unfamiliar midwives Reduced Duration of labor and CS. Rates of Oxytocin use and 5-min Apgar scores were similar in both groups.
Kennell [34] 1991 USA 412 Trained unfamiliar community doula Reduction in CS, instrumentation, analgesic usage, oxytocin use, duration of labor, and infant hospitalization.
Klaus [35] 1986 Guatemala 417 Unfamiliar, untrained community doula Reduction in duration of labor, CS, oxytocin augmentation, and NICU admissions.
Langer [36] 1998 Mexico 710 Unfamiliar retired nursing officers Reduction in duration of labor, No effects on medical interventions, maternal psychology, or newborn’s condition
Madi [37] 1999 Botswana 109 Untrained female relative Increase in spontaneous vaginal delivery, Less intrapartum analgesia, Fewer instrumentations, and CS, Less oxytocin.
McGrath [12] 2008 USA 420 Unfamiliar trained doula Reduction in CS, analgesic usage, and positive experience with doula
Nikodem [38] 1998 South Africa 39 Unfamiliar, untrained community doula No differences in postpartum depression and Coppersmith self-esteem scores.
Robati [4] 2020 Iran 80 Unfamiliar midwives Decreased anxiety and pain during labor
Safarzadeh [6] 2012 Iran 150 Untrained friend/relative Reduced duration of labor, No difference in pain severity.
Salehi [7] 2016 Iran 84 Trained husband/friend/relative Reduced maternal anxiety
Shahshahan [8] 2012 Iran 50 Familiar, untrained support person Reduction in labor and labor pain duration, Increased maternal satisfaction, and No difference in 5-min Apgar score and instrumentation.
Torres [39] 1999 Chile 435 Trained familiar companion No difference in spontaneous vaginal deliveries, intrapartum analgesic use, oxytocin use, cesarean birth, and instrumentation.
Trotter [40] 1992 South Africa 63 Unfamiliar, untrained community doula Reduced incidence of postpartum depression
Trueba [41] 2000 Mexico 100 Trained unfamiliar doula Reduction in CS, Duration of labor, and analgesic usage.
Wolman [42] 1993 South Africa 149 Unfamiliar, untrained community doula Increased self-esteem, Decreased postpartum depression and anxiety.
Yeonyong [3] 2012 Thailand 114 Trained relative Shorter duration of labor, Increased maternal satisfaction, No difference in spontaneous vaginal deliveries.
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CS–Cesarean Section, NICU–Neonatal Intensive Care Unit

The funnel plots for each primary meta-analysis exhibited symmetry, suggesting minimal publication bias. Figs 2 and 3 summarize the original version of the Cochrane Risk of Bias tool assessment of RCTs. All the studies show an overall high risk of bias due to having unclear risk for multiple domains or a high risk of bias in at least one domain [43]. As expected, the highest risk of bias is reported in the blinding of participants and personnel (Fig 3).

Fig 2. Risk of bias summary.

Fig 2

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Green: Low risk, Red: High risk, Blank: Unclear risk.

Fig 3. Risk of bias graph.

Fig 3

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Primary analysis

Table 2 reports a meta-analysis of 8 outcomes as risk ratios and standard mean differences with 95% confidence intervals. The highest overall effect is the improvement reported in the 5 min Apgar score < 7 by 1.52(95% CI 1.05,2.20). All the outcomes are statistically significant, but most show a moderate to low effect size. Considerable heterogeneity is also reported in all results except for 5-minute Apgar < 7 and instrumental delivery. Fig 4 displays the forest plot for the meta-analysis of the 5-minute Apgar score.

Table 2. Effectiveness of a labor companion related to 8 outcomes.

Outcome No. of Participants (Studies) RR (95% CI) P value Heterogeneity
(I2)
1. Spontaneous vaginal delivery 13811
(19 RCTs)		 1.09(1.04,1.13) 0.0001 64%
2. Duration of labor (Hours) (Standard mean difference) 5422
(17 RCTs)		 0.30(0.18,0.41) 0.0001 72%
3. Cesarean section 15080
(24 RCTs)		 1.43(1.20,1.71) 0.0001 63%
4. Instrumental delivery 13955
(21 RCTs)		 1.13(1.03,1.23) 0.008 23%
5. Oxytocin for labor induction 12958
(21 RCTs)		 1.10(1.01,1.19) 0.03 71%
6. Analgesic usage 12719
(18 RCTs)		 1.06(1.01,1.11) 0.02 52%
7. Tocophobia 11133
(11 RCTs)		 1.46(1.26,1.68) 0.0001 63%
8. 5 min Apgar < 7 12539
(16 RCTs)		 1.52(1.05,2.20) 0.03 12%
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RCT–Randomized Controlled Trial, RR–Relative Risk, CI–Confidence Interval

Fig 4. Forest plot for the meta-analysis of 5-minute Apgar score < 7.

Fig 4

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Secondary analysis

Familiar versus unfamiliar labor companion

Table 3 shows the subgroup analysis of the same eight outcomes shown in Table 2 for familiar versus unfamiliar labor companions. Subgroups based on trial or patient characteristics that modified outcomes were considered for statistical significance. P value from the test for subgroup difference was used to assess statistically significant subgroup differences. P<0.1 indicates a statistically significant subgroup difference [44]. There was no difference in outcomes in the subgroup analysis except for tocophobia (p = 0.02). Therefore, having a familiar labor companion reduced Tocophobia significantly. There was no significant subgroup heterogeneity concerning tocophobia within either subgroup. The combined effect size for Tocophobia was 1.73 (95% CI 1.49,2.02) for the familiar labor companion subgroup and 1.34 (95% CI 1.14,1.58) for the unfamiliar labor companion subgroup. However, there was an unequal distribution of trials and participants between the familiar and unfamiliar companion subgroups in all subgroup analyses. Nevertheless, for all eight outcomes, the pooled effect size for each subgroup favored having a continuous labor companion. Fig 5 displays the forest plot for the subgroup analysis of tocophobia.

Table 3. Effectiveness of having a familiar versus unfamiliar labor companion.
Outcome No. of Participants (Studies) RR (95% CI) P value Heterogeneity
(I2)		 Test for subgroup difference (p-value)
1. Spontaneous vaginal delivery Familiar 1706
(7 RCTs)		 1.12(0.99,1.28) 0.07 80% 0.6
Unfamiliar 12105
(12 RCTs)		 1.08(1.04,1.13) 0.0002 60%
2. Duration of labor (Hours) Familiar 1335
(4 RCTs)		 0.31(0.20,0.41) 0.0001 0% 0.94
Unfamiliar 4087
(13 RCTs)		 0.31(0.16,0.46) 0.0001 77%
3. Cesarean section Familiar 2284
(8 RCTs)		 1.55(1.00,2.39) 0.05 76% 0.63
Unfamiliar 12796
(16 RCTs)		 1.38(1.14,1.67) 0.001 54%
4. Instrumental delivery Familiar 1752
(8 RCTs)		 1.12(0.95,1.32) 0.19 22% 0.81
Unfamiliar 12203
(13 RCTs)		 1.15(1.01,1.30) 0.03 31%
5. Oxytocin for labor induction Familiar 2289
(8 RCTs)		 1.09(0.93,1.27) 0.28 79% 0.39
Unfamiliar 10669
(13 RCTs)		 1.20(1.03,1.38) 0.02 78%
6. Analgesic usage Familiar 2075
(7 RCTs)		 1.07(0.97,1.18) 0.21 61% 0.95
Unfamiliar 10644
(11 RCTs)		 1.07(1.01,1.14) 0.03 48%
7. Tocophobia Familiar 1708
(4 RCTs)		 1.73(1.49,2.02) 0.0001 29% 0.02
Unfamiliar 9425
(7 RCTs)		 1.34(1.14,1.58) 0.0004 48%
8. 5 min Apgar < 7 Familiar 1749
(8 RCTs)		 2.40(0.93,6.17) 0.07 36% 0.21
Unfamiliar 10790
(8 RCTs)		 1.25(0.88,1.79) 0.22 0%
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RCT–Randomized Controlled Trial, RR–Relative Risk, CI–Confidence Interval

Fig 5. Forest plot for the subgroup analysis of tocophobia.

Fig 5

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Trained versus untrained labor companion

We analyzed trained versus untrained labor companions in a subgroup analysis. The pooled effect size, irrespective of companion training, favored the presence of a labor companion for all outcomes. Only two outcomes, namely tocophobia (p = 0.004) and cesarean section (p = 0.02), differed between the subgroups. These findings suggest that companion training significantly negatively impacts these outcomes, which is difficult to explain. However, subgroup heterogeneity concerning tocophobia was significant within the trained companion group (I2 = 59%) but not in the untrained companion group (I2 = 0%). Conversely, subgroup heterogeneity was insignificant within the trained companion group (I2 = 44%) but significant within the untrained companion group (I2 = 54%) in relation to the CS rate. For the analysis of Tocophobia, the pooled effect sizes were denoted as 1.34 (95% CI 1.14,1.57) and 1.84 (95% CI 1.60,2.12) in the trained versus untrained subgroup comparisons. At the same time, the CS rate was represented at 1.22 (95% CI 1.05, 1.42) and 2.16 (95% CI 1.37, 3.40), respectively. There was a notable imbalance in the distribution of trials and participants between the trained and untrained companion subgroups across all eight outcomes (S1 Table).

Effectiveness of labor companion before and after 2000

Out of the eight outcomes analyzed, a statistically significant subgroup difference was observed only in the duration of labor (p = 0.004), suggesting that the classification of RCTs as before and after 2000 has a significant impact. Notably, subgroup heterogeneity was significant within the subgroup of RCTs conducted after 2000 (I2 = 74%) but not in the subgroup of RCTs conducted before 2000 (I2 = 44%) concerning the duration of labor. The pooled effect size for the duration of labor was 0.16 (95% CI 0.06,0.26) for the subgroup of RCTs conducted before 2000 and 0.53 (95% CI 0.30,0.77) for the subgroup of RCTs conducted after 2000. However, there was an uneven distribution of trials and participants between subgroups in all subgroup analyses. Nevertheless, having a continuous labor companion consistently showed a favorable pooled effect size in all eight outcomes (S2 Table).

Effectiveness of labor companions in different geographical regions

Table 4 summarizes the effect of having a labor companion in different geographical regions such as Asia, Africa, and Europe. A significant subgroup difference (p<0.1) was found in relation to the duration of labor, CS rate, oxytocin for labor induction, analgesic usage, and tocophobia, indicating that ethnic differences significantly influence these outcomes. The most significant overall effects are seen in Asia, followed by Africa. Effects are minimal in the European region. However, there was an uneven distribution of trials and participants between subgroups in all analyses, with the highest number of participants in the European subgroup.

Table 4. Effects of having a labor companion in different geographical regions.

Outcome No. of Participants (Studies) RR (95% CI) P value Heterogeneity
(I2)		 Test for subgroup difference (p-value)
1. Spontaneous vaginal delivery Asia 464
(4 RCTs)		 1.18(0.84,1.64) 0.35 94% 0.77
Africa 298
(2 RCTs)		 1.13(0.92,1.39) 0.24 67%
Europe 2366
(5 RCTs)		 1.06(1.01,1.11) 0.02 0%
2. Duration of labor Asia 327
(4 RCTs)		 0.67(0.16,1.19) 0.002 80% 0.02
Africa 774
(2 RCTs)		 0.28(0.07,0.48) 0.008 41%
Europe 2374
(5 RCTs)		 0.09(-0.03,0.21) 0.15 40%
3. Cesarean section Asia 386
(4 RCTs)		 2.57(1.29,5.12) 0.007 44% 0.02
Africa 883
(3 RCTs)		 2.02(1.16,3.52) 0.01 42%
Europe 2509
(6 RCTs)		 1.12(0.84,1.48) 0.44 0%
4. Instrumental delivery Asia 264
(3 RCTs)		 0.86(0.47,1.56) 0.62 0% 0.43
Africa 298
(2 RCTs)		 1.82(0.42,7.93) 0.43 64%
Europe 2509
(6 RCTs)		 1.21(1.05,1.39) 0.009 0%
5. Oxytocin for labor induction Asia 427
(5 RCTs)		 1.16(0.95,1.43) 0.15 0% 0.07
Africa 883
(3 RCTs)		 1.24(0.83,1.84) 0.29 35%
Europe 2373
(5 RCTs)		 0.99(0.88,1.10) 0.81 40%
6. Analgesic usage Asia 114
(1 RCT)		 1.20(0.63,2.28) 0.59 NA 0.04
Africa 883
(3 RCTs)		 1.13(0.94,1.34) 0.18 25%
Europe 1965
(5 RCTs)		 1.10(1.01,1.21) 0.04 0%
7. Tocophobia Asia NA NA NA NA 0.003
Africa 773
(2 RCTs)		 1.83(1.58,2.11) 0.0001 0%
Europe 1560
(2 RCTs)		 1.19(0.85,1.67) 0.31 0%
8. 5 min Apgar < 7 Asia 364
(4 RCTs)		 6.22(1.39,27.84) 0.02 0% 0.58
Africa 294
(2 RCTs)		 1.14(0.49,2.67) 0.77 0%
Europe 2287
(4 RCTs)		 1.74(0.90,3.38) 0.10 0%
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RCT–Randomized Controlled Trial, RR–Relative Risk, CI–Confidence Interval

Discussion

Research gap

The advantages of continuous labor companionship are well recognized. However, implementing a labor companion policy lags behind the evidence and is met with significant resistance at all levels [45]. There is a wide range of definitions, outcomes, and indicators used to describe support by a labor companion, and there is a reporting heterogeneity leading to divided opinions. Also, scarce evidence is available to define the ideal labor companion.

Confounding factors affecting the total labor experience sometimes undermine the importance of having a labor companion. Therefore, different levels of labor companions, from family members to trained healthcare workers, continue to play a role in obstetrics care delivery systems worldwide. This heterogeneity, while coloring the opinion within the local setting, seems to affect the quality of research published and thus leads to a lack of higher-level evidence on which healthcare managers can rely to support the use of "the best" labor companion. Our study attempts to standardize the optimum characteristics of the ideal labor companion, potentially leading to better labor experience across all settings, lesser labor complication rates, better cost-effectiveness, and, hopefully, universal implementation.

Summary of main results

This review included 35 RCTs involving 16414 participants, conducted in hospital settings in 18 countries, highlighting significant positive effects of continuous labor support across various outcomes. The primary analysis showed the highest overall effect in the improvement reported in the 5-minute Apgar score < 7, with an effect size of 1.52 (95% CI 1.05, 2.20). Also encouraging is that the mere presence of a labor companion improved all eight studied outcomes compared to the absence, regardless of subgrouping characteristics. The secondary analysis showed that familiar labor companions were better at reducing tocophobia, with an effect size of 1.73 (95% CI 1.49, 2.42), compared to unfamiliar companions, with an effect size of 1.34 (95% CI 1.14, 1.58). Untrained labor companions were the better choice in reducing tocophobia and the cesarean section rate compared to trained companions. For the analysis of tocophobia, the pooled effect sizes were 1.34 (95% CI 1.14, 1.57) and 1.84 (95% CI 1.60, 2.12) in trained versus untrained subgroup comparisons. For the cesarean rate, they were represented as 1.22 (95% CI 1.05, 1.42) and 2.16 (95% CI 1.37, 3.40), respectively. The pooled effect size for the duration of labor was 0.16 (95% CI 0.06, 0.26) for the subgroup of RCTs conducted before 2000 and 0.53 (95% CI 0.30, 0.77) for the subgroup of RCTs conducted after 2000. A significant subgroup difference (<0.1) was found in relation to the duration of labor, cesarean section rate, oxytocin for labor induction, analgesic usage, and tocophobia in the subgroup analysis of geographical regions, indicating that ’geographical setting’ modifies the outcomes in a statistically significant way.

Impact of labor companionship on emergency cesarean section rates

Cesarean section rates continued to rise through the last few decades, resulting in significant medicalizing of labor and higher healthcare costs with doubtful accruing benefits [46]. Although labor companionship has a low to moderate effect on reducing cesarean sections [10, 17, 29, 31], it is a useful strategy to incorporate into a broader plan. By overlapping beneficial effects of lowering tocophobia, the ability of effectively directed pushing, and shorter labor duration, the contribution of a labor companion towards reducing cesarean section rates is incontrovertible [3, 7, 32, 42].

Tocophobia increases the stress and sympathetic response in the mother during labor. Maternal stress reactions are associated with fetal tachycardia and variable decelerations [5, 6]. The resultant cardiotocography changes may lead to high cesarean section rates. As the management protocols used during abnormal CTG events during the studies were unavailable, the effect could not be analyzed further in the available dataset.

Impact of labor companionship on neonatal outcome

Apgar score at 5 minutes is more explicit of intrapartum fetal condition [47], which is improved by having a labor companion; therefore, labor companionship can help reduce neonatal intensive care unit and special care baby unit admissions. This is likely a cumulative effect of less stressful labor with lower maternal catecholamine levels. Our results revealed a significant improvement in the five-minute Apgar score in the presence of a labor companion, irrespective of the type of companion. Several studies have looked at the possibility of continuing the support provided by the labor companion into neonatal care support and beyond [9, 16, 36]. The authors agree that the role of the labor companion does not have to stop at the baby’s delivery; it may continue through the first few months of motherhood and recommend further directed research into the topic.

Impact of labor companionship on intrapartum and postpartum psychological well-being

The presence of a labor companion during childbirth has been shown to improve maternal satisfaction [17, 24, 26, 28], boost maternal self-esteem [26, 38], reduce postpartum depression [38, 40, 42], reduce anxiety [7, 13, 32] and improve overall psychological well-being [6, 21, 36]. Due to the heterogeneity of tools used for assessing maternal satisfaction, self-esteem, and postpartum depression, meta-analysis was not possible. However, tocophobia was reported homogeneously among different studies. Tocophobia is a form of extreme anxiety about labor that, in some, may amount to post-traumatic stress [2]. The current study showed that familiar and untrained labor companions better alleviate tocophobia than unfamiliar and trained companions. A familiar labor companion/companion of choice may have a close emotional bond with a laboring mother compared to a newly introduced unfamiliar labor companion. Formal training as a labor companion may attribute distance in the emotional bond when adhering to the instructed protocols, increasing anxiety. Studies have shown that labor companionship can affect the long-term psychological well-being of the mother [38, 40, 42], which is a potential area for further research.

Comparative effectiveness of familiar versus unfamiliar labor companionship

Comparing familiar and unfamiliar labor companions revealed a larger effect size in our study, favoring familiar labor companions in achieving successful vaginal delivery, having shorter labor, lower section rates, lower tocophobia rates, and fewer neonates with Apgar <7 at 5 minutes. Familiarity and attachment between the laboring mother and the companion are likely to provide better support and meet the expectations of the parturient during labor. It is uncommon to have a familiar labor companion who is also trained. Therefore, it is more likely that the effect is due to familiarity rather than the training they have received. Some studies observed that with familiar labor companions, women are less likely to adopt optimal positions during labor which are proven to shorten labor duration and reduce assisted vaginal deliveries [3]. They are more likely to stay in the most comfortable position, which sometimes may be counterproductive. With trained support, women tend to stay in lateral or upright positions during labor without epidurals and lateral positions with epidurals [4]. However, our results suggest that this criticism has no significant impact and is no reason to deny a companion of choice.

While most studies use low-risk mothers to mitigate the difficulties in exploring labor with medical and fetal complications, according to the authors’ best knowledge, there are no RCTs involving mothers with complicated pregnancies. Pregnant mothers with heart diseases would likely find it beneficial in terms of cardiac status to have less pain and less anxiety with a familiar labor companion. We feel the impact of labor companions in medically complicated pregnancies is an area needing urgent further exploration.

Training of labor companions versus making trained labor companions familiar

Current consensus suggests extending midwifery care to ensure the likelihood of having a familiar carer during labor. From early pregnancy, closer, more personal, coordinated shared care by the community and hospital-based midwives have the potential to make a familiar, trained labour caregiver available during the labor.

However, this does not replace the role of a labor companion. Labour companion, by definition, is not involved in the medical needs of the parturient. A fully trained and qualified labour caregiver is a luxury even in developed economies, and the shortage of midwives is acute globally. A labour caregiver as a companion is unlikely to be economically viable.

A viable strategy would be to select a familiar labor companion early in the pregnancy and provide suitable training to them integrated into the existing antenatal education program conducted by hospital-based and field midwives.

It is unclear whether a trained labour companion provides more effective cover than simply a familiar labour companion or whether the women should choose a familiar companion and that companion can undergo training for the role. Developing such training programs may not be cost-effective, considering the significant advantages of having an untrained, familiar labor companion per laboring mother with trained staff to oversee the entire process. It is clear from other studies comparing psychological and emotional responses toward laboring women that training should include a psychological component and highlight empathy as one of the most important characteristics of a labor companion, and such training is hard to implement [7, 13, 32, 38, 40]. Further, there should be regular validation, certification, and continuous professional development for these trained labor companions.

There is insufficient data to assess the similarities of labor companion training associated with the included studies. Only some papers gave short descriptions of how the training was conducted [34, 35, 37, 39]. Also, healthcare workers with different levels of training and experience were employed as labor companions in the included studies [5, 25, 28, 29]. Determining minimum labor companion training standards within the current analysis is challenging.

In summary, it is unclear whether the training for the role affects a labour companion’s effectiveness. Also unclear is the relative importance of familiarity versus the training labour companions receive. Familiar companions tend not to have received any training, but they seem effective based on an indirect analysis of the results. Whether the training being provided somehow reduces the effectiveness of labour companions who would otherwise be more effective is also a consideration. Overall, this area needs more research to understand the relationship.

Choosing the ideal support person

There is no evidence to determine who would be the best labor companion. The available studies involved friends, female relatives, healthcare professionals, or community personnel. Only one study used a partner as a labor companion [7], which may be due to cultural reasons or privacy issues of other women in the labor care setting or lack of invitation for male partners to participate in the labor process actively. This is a potential area for further research. It would be interesting to compare different relatives acting as labor companions. Due to complex relationship dynamics and cultural differences, it would be very difficult to conduct and interpret such a study. Some cultures are more reluctant to accept the male partner as the labor companion. In resource-poor labor room settings, it would be unethical to do so if it is difficult to maintain the privacy of laboring women. High heterogeneity is a limitation of this study in providing recommendations on the ideal labor companion. Presently, local protocols accounting for local cultural beliefs would be of superior benefit.

The current resource-poor labor room settings do not give any room for direct family involvement. Due to limitations in funding and staffing, there are hardly any waiting areas for the family to stay during the labor of their loved one. The labor companion may also require support during their role, and waiting areas may just be what they need to wind down. On the flip side, we also need to consider the ramifications of such an arrangement in the spectrum of worldwide social norms.

Temporal evolution of study data

The temporal differences between studies conducted before 2000 and later, as demonstrated in our research, can be due to the recorded rise of cesarean section rates after 2000. Also, with international consensus, there has been a marked improvement in the methodological quality of randomized controlled trials since 2000, especially with the introduction of trial registries in 2006. The findings may also be due to changes in labor management guidelines and better availability of fetal and maternal monitoring facilities. More spontaneous vaginal deliveries may have occurred before the year 2000, while with a modern understanding of fetal physiology and the availability of continuous electronic monitoring, interventions may have become more likely. With the previous linear understanding of labor durations, more cesarean sections may have occurred due to a suspected lack of progress compared to the current dynamic approach to stages of labor.

Comparative effectiveness according to geographic location

Differences in effect sizes of secondary outcomes between Asia, Africa, and Europe may be observed due to regional differences in obstetric practice. Asia and Africa, accounting for most of the world’s lower-middle-income economies, lack some basic facilities widely available on the European continent. Obstetricians, therefore, make decisions based on the overall situation rather than following strict guidelines. In using the positive influence of labor companionship, it is not surprising that more cesarean deliveries can be prevented in Asian and African regions compared to Europe. Since the cost of a cesarean delivery is much higher compared to that of a vaginal delivery, the opportunity-cost saving would be much higher [48].

There are no studies assessing the acceptability of having a labor companion. There are established acceptability constructs that can address both patients’ and healthcare workers’ points of view [49]. Well-conducted studies would provide further evidence for incorporating the practice into routine labor care everywhere, especially in low-resource settings. Also, attitudes towards having a labor companion must be assessed based on established questionnaires. While no such studies exist, further research would be of enormous value.

Creating awareness among the public would be essential in incorporating this paradigm-shifting practice into routine obstetric care. It would circumvent any possible backlash from different mindsets and social backgrounds.

Strengths and limitations

We harnessed the strength of rigorous research, utilizing data from 35 RCTs, and delved deeply into the nuances of labor companionship, scrutinizing factors like familiarity versus unfamiliarity, trained versus untrained companions, and temporal associations—an approach not previously explored in existing meta-analyses [50]. This comprehensive examination provides valuable insights into the impacts of labor companionship that go beyond what has been previously studied.

Labor companions have been proven to significantly benefit fetal and maternal health in various setups and settings. However, universal uptake is lagging. The causes for the lagging can be multifactorial, where problems with implementation are partly responsible [45]. Some research questions concerning the role of labor companions demand high-quality evidence, typically sourced from RCTs. Conversely, questions regarding maternal satisfaction and staff attitudes toward labor companions usually do not warrant RCTs or can be adequately addressed using alternative methodologies. We conducted a thorough review of RCTs to provide answers where rigorous evidence was crucial while also employing meta-analysis to bridge research gaps.

The current study does come with its limitations. All 35 RCTs included in our analysis exhibited a high degree of bias due to unblinding, as blinding is impossible due to the nature of the intervention, a necessary limitation. We used the older original version of the Cochrane Risk of Bias tool rather than the more recent version 2 of the Cochrane Risk of Bias tool (RoB-02). Due to significant heterogeneity in reporting across the trials, we could only identify eight distinct outcomes with sufficient studies, limiting our ability to perform robust subgroup analyses.

All the analyzed RCTs, especially the three with the highest weight, had spontaneous onset of labor as an inclusion criterion. Therefore, the results may not be applicable in an induced labor setting. Since spontaneous labor leads to more successful vaginal deliveries, less use of oxytocin augmentation, less assisted vaginal deliveries, shorter labors, and less analgesia use compared to induced labor, the effect of a labor companion alone may not be so profound in this analysis. Studies comparing similar outcomes between spontaneous and induced labor in the presence of a labor companion would help clarify the issue.

Recommendations

Future research into labor companionship should prioritize conducting well-designed RCTs with a rigorous methodology to mitigate bias and improve the quality of evidence in this area. Additionally, efforts should be made to standardize reporting practices to enhance comparability across studies and facilitate more extensive subgroup analyses. This would result in minimal heterogeneity, paving the way to a robust meta-analytical evidence base to form recommendations. In the interim, healthcare providers should engage in shared decision-making with expectant mothers, considering their preferences and individual circumstances when considering labor companions.

Well-designed qualitative studies that assessed satisfaction with labor, acceptability, and stress experienced during labor using validated tools and quantification methods like the Likert Scale would add significant value to the evaluation of the psychological and emotional component of the labor process.

Conclusion

Labor companionship demonstrates potential benefits across various maternal and neonatal outcomes. However, the type of best labor companion remains inconclusive. While a labor companion may not have as profound an effect in spontaneous labor compared to induced labor scenarios, it still contributes to improved birthing experiences and reduced cesarean section rates. A familiar, untrained companion offers greater support during labor, emphasizing the importance of emotional connection. However, there are limitations, including study heterogeneity, a lack of data on companion training, and temporal differences in study outcomes. Despite these limitations, labor companionship can be a valuable strategy to incorporate into broader obstetric care plans.

Supporting information

S1 Table. Effectiveness of trained versus untrained labor companion.

(DOCX)

pone.0298852.s001.docx (13.1KB, docx)
S2 Table. Effectiveness of a labor companion before and after 2000.

(DOCX)

pone.0298852.s002.docx (13KB, docx)
S1 File. Analysis of spontaneous vaginal delivery.

(DOCX)

pone.0298852.s003.docx (139.3KB, docx)
S2 File. Analysis of duration of labor.

(DOCX)

pone.0298852.s004.docx (132.9KB, docx)
S3 File. Analysis of cesarean section.

(DOCX)

pone.0298852.s005.docx (154KB, docx)
S4 File. Analysis of instrumental delivery.

(DOCX)

pone.0298852.s006.docx (144.2KB, docx)
S5 File. Analysis of oxytocin for labor induction.

(DOCX)

pone.0298852.s007.docx (148.8KB, docx)
S6 File. Analysis of analgesic usage.

(DOCX)

pone.0298852.s008.docx (134KB, docx)
S7 File. Analysis of tocophobia.

(DOCX)

pone.0298852.s009.docx (115.7KB, docx)
S8 File. Analysis of 5 min Apgart < 7.

(DOCX)

pone.0298852.s010.docx (104.5KB, docx)
S9 File. PRISMA 2020 checklist.

(DOCX)

pone.0298852.s011.docx (27.5KB, docx)
S10 File. Detailed search strategy.

(DOCX)

pone.0298852.s012.docx (18.8KB, docx)
S11 File. Study protocol.

(PDF)

pone.0298852.s013.pdf (144KB, pdf)
S12 File. Summary data.

(DOCX)

pone.0298852.s014.docx (36.5KB, docx)

Data Availability

All relevant data are within the manuscript and its Supporting Information files.

Funding Statement

The author(s) received no specific funding for this work.

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Decision Letter 0

Tanya Doherty

26 Mar 2024

PONE-D-24-02940Impact of continuous labour companion- who is the best: A comprehensive meta-analysis on familiarity, training, temporal association, and geographical locationPLOS ONE

Dear Dr. Jayasundara,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

The reviewers have suggested some revisions to your article. Please address these according to the instructions below.

Please submit your revised manuscript by May 10 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

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If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

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We look forward to receiving your revised manuscript.

Kind regards,

Tanya Doherty, PhD

Academic Editor

PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: I Don't Know

Reviewer #2: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Thank you for the opportunity to review this article. I enjoyed reading about this interesting study. The article described the results of a meta-analysis of 35 RCTs on labour companionship and maternal and neonatal outcomes. The study aimed to determine if labour companion training or familiarity had an effect on these outcomes. Overall, the article is well-written and presented and I felt that it would make a useful contribution to the literature. My main concern was with the discussion section which I felt should be revised to include a more substantial engagement with the existing literature in this area.

Introduction

The introduction provides a useful overview of the emotional labour experience and how fear and anxiety may play a role in labour outcomes as well as the role of labour companions in improving the labour experience. A clear rationale for the current study was presented. My only suggestions here would be to include definitions for some of the key concepts which are used throughout the article. Eg tokophobia and to perhaps reconsider the use of the term ‘developing countries’ possibly in favour of LMICs?

Method

Generally, I felt that the necessary information was reported in this section.

Results

The results of the analysis were clearly presented with helpful tables complementing the text. I do not have the expertise to assess the rigour of the statistical analysis and so would recommend an additional reviewer with the requisite experience evaluate this.

Discussion

The discussion was interesting, however, my main concern is the lack of literature in this section. I also had a few more minor questions and suggestions.

Tokophobia vs tokophobia- one spelling should be used consistently.

The possible mechanisms through which labour companionship may be influencing APGAR score could be included on p19 lines 310-311.

References to the studies being referred to on line 316 should be included on p19.

Some of the definitions and explanations in the discussion section could be included in the introductory section for example lines 317-320 on p19.

Lines 332-336. The discussion of the role of familiar vs unfamiliar labour companions on birthing positions was interesting but again references to the other studies referred to should be included- (lines 332-336) and I felt that the links to the data in the present study could be made clearer. The implications for future research/practice of this observation could also be unpacked.

Lines 343 and 347, the authors mention ‘the current resource poor labour room setting’ it may be helpful to mention that you are referring to the many contexts where resources are limited as at the moment it implies that everywhere is resource poor.

The discussion section as a whole could benefit from a deeper engagement with the literature, I don’t think there are any references in this section. Many of the claims made here are not supported with references to existing studies in this area which would significantly strengthen the arguments being made.

Recommendations

Perhaps the authors could acknowledge the challenges of reducing bias in studies like the ones included in this article. I also wondered about how qualitative studies exploring the perspectives of birthing women and labour companions might compliment the RCTs on this topic.

Conclusion

The conclusion provided a good summary of some of the key points made in the article although the recommendation to standardize companion training did not feature in the recommendations section and was not really indicated from the results of the study and so could perhaps be removed.

Reviewer #2: Manuscript #: PONE-D-24-02940

Title: Impact of continuous labour companion- who is the best: A comprehensive meta-analysis on familiarity, training, temporal association, and geographical location

Authors: DMCS Jayasundara; IA Jayawardane; SDS Weliange; TDKM Jayasingha; TMSSB Madugalle

Article type: Research Article

Thank you for the opportunity to review this important work.

I should congratulate the authors on this meticulous work, which is publishable in PLOS ONE. However, I would like to suggest a few comments to improve the scientific validity and readability of the manuscript.

Title

Suggest adding a ‘systematic review and meta-analysis of randomised controlled trials’ to the title. Please make sure the title is not too long.

Abstract

Mention the timeline of your search.

Please explain how funnel plots are used to assess the risk of bias. Funnel plots are used to assess the publication bias.

Prospective registration of the protocol indicates the transparency of the work. Could you please mention whether this work was registered prospectively? If not, explain.

CI – You need to word it out before using it as an abbreviation.

APGAR – This is not an abbreviation. Regina Apgar introduced this score. Please correct this as Apgar throughout the manuscript.

Line 40-43: Please add the summary statistics for the results. There is a difference between a lay language summary and a scientific abstract. Please have a look at a Cochrane review of the way they have presented the results.

Line 44: Add systematic review and meta-analysis. It is unclear why the authors mentioned underscoring the benefits of labour companionship. It is not clear; please rephrase.

The discussion/conclusion needs to be rephrased for clarity.

Main text

Line 96-97: Tokophobia and tokophobia are used interchangeably. Please use one. Please provide a definition for tocophobia.

As this topic is interesting and broad, it would be great if the authors could introduce a few subheadings to each section. The introduction can be divided into background/literature review/gap of knowledge/objectives, etc. The same applies to the other sections: methods, results, and discussion.

Line 106: was the search from inception to 04-07-2023? Please mention.

Line 177: Can you provide references for these meta-analyses? Perhaps you could discuss these with your findings in the discussion section.

Line 118: I suggest this part should go into a subheading, such as screening eligible studies. Please mention the initials of each author responsible for reviewing. Generally, conflicts between the primary and second reviewers are resolved by a third reviewer, if required.

Please add a sub-title explaining all the categories: familiar versus unfamiliar, trained versus untrained, and what temporal association is.

How did you divide the geographical territory? WHO has a categorization.

Line 130: add ‘viable’ singleton pregnancies

Line 130: early labour, more accurately, the latent phase.

Line 132: please explain what you mean by genital abnormalities here

Lines 133-134: What about quasi-experimental studies? Otherwise, you can simply mention that any other study designs, other than randomised controlled trials, including quasi-experimental trials, were excluded. Did you have limitations for the article language? Were all the articles in English?

Line 135: Suggest not mixing the study outcomes with the data extraction and quality assessment. Study outcomes should be a separate subtopic followed by another subtopic for the ‘Risk of bias and quality assessment’- RoB2 and possible biases. In the study outcomes, please mention primary and secondary outcomes clearly.

Line 144-146: Risk of bias assessment – I am not sure the authors have used the current RoB -2 tool as the domains that appear on the manuscript are different from the RoB -2. Looks like authors have used RoB -01. Please update accordingly.

Please go to this link for more information on RoB 2: https://sites.google.com/site/riskofbiastool/welcome/rob-2-0-tool/current-version-of-rob-2

Line 150-160: Suggest using ‘versus’ instead of ‘vs’.

Table 1: Please provide what LSCS means as a footnote. All tables/figures should be self-explanatory. Can not use RCT in the table legend. Please word it out.

Table 1: What is the order of appearance of the RCTs in Table 1? It should be either the chronological order of appearance, A-Z or any other rational categorization.

Table 1, 6th column: what are these outcomes? Are these the primary outcomes reported by the trials? Or else all the outcomes? It would be more explanatory to divide primary and secondary outcomes.

Line 219: There cannot be more than one funnel plot to assess the publication bias for one meta-analysis. Could you please elaborate more?

Line 220-221: Inability to blind is a limitation; please acknowledge this in the discussion.

In Tables 2/3/4, I2 for heterogeneity appears as a decimal value. Is this a mistake? According to the Cochrane Handbook, I2 should be 0-100% as a percentage.

Line 260: cesarean section, which is abbreviated as LSCS. Please correct.

Suggest American English terms like labor, not ‘labour’ throughout the manuscript.

Table 4: 6th column – please explain what you mean by the test for subgroup difference.

Discussion:

- The first paragraph needs to be rewritten for clarity. It should start with the research gap and objective and end with the main findings.

- Please divide the entire discussion into separate sections as sub-topics to increase the readability of the paper. Please follow the steps of a well-written systematic review publication in a reputed journal. For example: Main findings, Critical review of literature, Strengths and limitations, Conclusions, Recommendations, Future directions etc.

- Line 312: Define ICU/SCBU abbreviations

Reference list:

None of the references have included the journal name.

I hope this might improve this work towards publication.

Thank you.

**********

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Reviewer #1: No

Reviewer #2: No

**********

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Attachment

Submitted filename: PLOS ONE Review March 25 2024.docx

pone.0298852.s015.docx (20.2KB, docx)
PLoS One. 2024 Jul 23;19(7):e0298852. doi: 10.1371/journal.pone.0298852.r002

Author response to Decision Letter 0

9 May 2024

We thank the reviewers and the editorial office for the excellent comments, suggestions, and advice on improving our meta-analysis. We have accepted all comments, and the article was amended accordingly. Details of the amendments are given below.

Comments to the Author

Reviewer #1: Thank you for the opportunity to review this article. I enjoyed reading about this interesting study. The article described the results of a meta-analysis of 35 RCTs on labour companionship and maternal and neonatal outcomes. The study aimed to determine if labour companion training or familiarity had an effect on these outcomes. Overall, the article is well-written and presented and I felt that it would make a useful contribution to the literature.

My main concern was with the discussion section which I felt should be revised to include a more substantial engagement with the existing literature in this area.

We thank the reviewer for the encouraging comments. We have revised the discussion, including a substantial engagement with the literature. We have rephrased the suggested areas for clarity. We have added definitions and possible mechanisms as instructed (Highlighted).

Introduction

The introduction provides a useful overview of the emotional labour experience and how fear and anxiety may play a role in labour outcomes as well as the role of labour companions in improving the labour experience. A clear rationale for the current study was presented.

My only suggestions here would be to include definitions for some of the key concepts which are used throughout the article. Eg tokophobia and to perhaps reconsider the use of the term 'developing countries' possibly in favour of LMICs?

Response: We thank the reviewer for the comments. We have added a definition for tocophobia (Lines 65-66), labor companion (Lines 84-86), and doula (Line 84). We have also changed the term developing countries to LMIC (Line 87).

Method

Generally, I felt that the necessary information was reported in this section.

Results

The results of the analysis were clearly presented with helpful tables complementing the text. I do not have the expertise to assess the rigor of the statistical analysis and so would recommend an additional reviewer with the requisite experience evaluate this.

Discussion

The discussion was interesting, however, my main concern is the lack of literature in this section. I also had a few more minor questions and suggestions.

Response – Thank you. Citations to studies mentioned in the discussion segment have been added, and the discussion expanded to reflect engagement with the current literature.

Tokophobia vs tocophobia- one spelling should be used consistently.

Response – Thank you. Tocophobia has been used as the spelling of choice.

The possible mechanisms through which labour companionship may be influencing APGAR score could be included on p19 lines 310-311.

Response – Thank you. We have amended the discussion with the possible mechanisms mentioned (Line 377-378).

References to the studies being referred to on line 316 should be included on p19.

Response – Thank you. Included within the citations/bibliography (Lines 386-388)

Some of the definitions and explanations in the discussion section could be included in the introductory section for example lines 317-320 on p19.

Response – Thank you. The definition of tocophobia has been included in the introduction (Lines 65-66)

Lines 332-336. The discussion of the role of familiar vs unfamiliar labour companions on birthing positions was interesting but again references to the other studies referred to should be included- (lines 332-336) and I felt that the links to the data in the present study could be made clearer.

Response – Thank you. We have rephrased for clarity, and references were added (Line 403-409)

The implications for future research/practice of this observation could also be unpacked.

Response – Thank you. We have discussed implications for future research/practice in a separate paragraph. (Line 409-412)

Lines 343 and 347, the authors mention 'the current resource poor labour room setting' it may be helpful to mention that you are referring to the many contexts where resources are limited as at the moment it implies that everywhere is resource poor.

Response – Thank you. We agree. Rephrased for clarity (Line 451 and 456)

The discussion section as a whole could benefit from a deeper engagement with the literature, I don't think there are any references in this section. Many of the claims made here are not supported with references to existing studies in this area which would significantly strengthen the arguments being made.

Response – Thank you. We have supported the claims with existing evidence (Citations added)

Recommendations

Perhaps the authors could acknowledge the challenges of reducing bias in studies like the ones included in this article. I also wondered about how qualitative studies exploring the perspectives of birthing women and labour companions might compliment the RCTs on this topic.

Response – We have reviewed the recommendations and added a discussion on possible value addition by qualitative studies (Lines 521 – 524)

Conclusion

The conclusion provided a good summary of some of the key points made in the article although the recommendation to standardize companion training did not feature in the recommendations section and was not really indicated from the results of the study and so could perhaps be removed.

Response – We agree. Removed.

Reviewer #2: Manuscript #: PONE-D-24-02940

Title: Impact of continuous labour companion- who is the best: A comprehensive meta-analysis on familiarity, training, temporal association, and geographical location

Authors: DMCS Jayasundara; IA Jayawardane; SDS Weliange; TDKM Jayasingha; TMSSB Madugalle

Article type: Research article

Thank you for the opportunity to review this important work. I should congratulate the authors on this meticulous work, which is publishable in PLOS ONE. However, I would like to suggest a few comments to improve the scientific validity and readability of the manuscript.

Title

Suggest adding a 'systematic review and meta-analysis of randomised controlled trials' to the title. Please make sure the title is not too long.

Response: We thank the reviewer for the encouraging evaluation and the suggestions for improvement. We have changed the title to,

Title: The impact of continuous labor companion- who is best: A systematic review and meta-analysis of randomized controlled trials.

Abstract

Mention the timeline of your search.

Response: We have added the timeline of our search (Line 29)

Please explain how funnel plots are used to assess the risk of bias. Funnel plots are used to assess the publication bias.

Response: We acknowledge that the funnel plots are used to assess the risk of publication bias and not to assess the risk of bias. We have amended accordingly (Line 31)

Prospective registration of the protocol indicates the transparency of the work. Could you please mention whether this work was registered prospectively? If not, explain.

Response: Thank you. We agree that the registration of systematic reviews has multiple scientific merits and includes prospective registration, strengthening transparency. The current study was rigorous in methodology and registered as an ongoing project with INPLASY. (Registration number: INPLASY202410003).

CI – You need to word it out before using it as an abbreviation.

Response: Thank you. We have corrected as instructed (Line 39)

APGAR – This is not an abbreviation. Regina Apgar introduced this score. Please correct this as Apgar throughout the manuscript.

Response: Thank you. We have corrected it as instructed.

Line 40-43: Please add the summary statistics for the results. There is a difference between a lay language summary and a scientific abstract. Please have a look at a Cochrane review of the way they have presented the results.

Response: Thank you. We have added summary statistics (Line 41-50)

Line 44: Add systematic review and meta-analysis. Amended discussion (Lines 51-58)

It is unclear why the authors mentioned underscoring the benefits of labour companionship. It is not clear; please rephrase. The discussion/conclusion needs to be rephrased for clarity.

Response: We acknowledge the reviewer's comment. We have amended it for a clearer discussion/conclusion (Lines 51-58)

Main text

Line 96-97: Tokophobia and tocophobia are used interchangeably. Please use one. Please provide a definition for tocophobia.

Response: We have changed to 'tocophobia' throughout the manuscript. Tocophobia is defined in the introduction (Lines 65-66)

As this topic is interesting and broad, it would be great if the authors could introduce a few subheadings to each section. The introduction can be divided into background/literature review/gap of knowledge/objectives, etc. The same applies to the other sections: methods, results, and discussion.

Response: Thank you. We have introduced subheadings to each section as instructed.

Line 106: was the search from inception to 04-07-2023? Please mention.

Response: We have added the exact timeline of our search (Line 115)

Line 177: Can you provide references for these meta-analyses? Perhaps you could discuss these with your findings in the discussion section.

Response: We added a reference in our supplementary S10 File- Detailed search strategy (Line 136). Also, we have added the reference in the discussion (Line 491)

Line 118: I suggest this part should go into a subheading, such as screening eligible studies.

Response: We have added a subheading as instructed (Line 127)

Please mention the initials of each author responsible for reviewing. Generally, conflicts between the primary and second reviewers are resolved by a third reviewer, if required.

Response: We have added the initials of the authors (Line 128-133)

Please add a sub-title explaining all the categories: familiar versus unfamiliar, trained versus untrained, and what temporal association is.

Response: We have added a new sub-title and explained all the categories (Line 168-176)

How did you divide the geographical territory? WHO has a categorization.

Response: Thank you. We used a continental basis to divide geographical territory. We have justified with references (Line 176)

Line 130: add 'viable' singleton pregnancies

Response: We added 'viable' (Line 141)

Line 130: early labour, more accurately, the latent phase.

Response: We agree. Added 'the latent phase' (Line 141)

Line 132: please explain what you mean by genital abnormalities here

Response: We acknowledge that we have mistakenly mentioned genital abnormalities. We have changed it to 'pelvic abnormalities not favor vaginal birth' (Line 144)

Lines 133-134: What about quasi-experimental studies? Otherwise, you can simply mention that any other study designs, other than randomised controlled trials, including quasi-experimental trials, were excluded. Did you have limitations for the article language? Were all the articles in English?

Response: We have changed as instructed (Lines 145-146 and 143)

Line 135: Suggest not mixing the study outcomes with the data extraction and quality assessment. Study outcomes should be a separate subtopic followed by another subtopic for the 'Risk of bias and quality assessment'- RoB2 and possible biases. In the study outcomes, please mention primary and secondary outcomes clearly.

Response: Thank you. We have amended the article to separately mention primary and secondary study outcomes (Line 158-166). We introduced a separate subtopic, risk of bias and quality assessment, as advised (Line 152-157).

Line 144-146: Risk of bias assessment – I am not sure the authors have used the current RoB -2 tool as the domains that appear on the manuscript are different from the RoB -2. Looks like authors have used RoB -01. Please update accordingly.

Please go to this link for more information on RoB 2: https://sites.google.com/site/riskofbiastool/welcome/rob-2-0-

tool/current-version-of-rob-2

Response: We acknowledge that we have used ROB 01 for the risk of bias assessment but not ROB 02. We amended the article to reflect the facts (Line 153-155)

Line 150-160: Suggest using 'versus' instead of 'vs'.

Response: We changed accordingly (Line 186-188)

Table 1: Please provide what LSCS means as a footnote. All tables/figures should be self-explanatory.

Response: We changed LSCS to CS throughout the article. We added a footnote (Line 247)

Can not use RCT in the table legend. Please word it out.

Response: Thank you. We have changed as instructed (Line 245)

Table 1: What is the order of appearance of the RCTs in Table 1? It should be either the chronological order of appearance, A-Z or any other rational categorization.

Response: We re-organized according to alphabetical order.

Table 1, 6th column: what are these outcomes? Are these the primary outcomes reported by the trials? Or else all the outcomes? It would be more explanatory to divide primary and secondary outcomes.

Response: These are the primary outcomes reported by the studies. We changed the column heading accordingly.

Line 219: There cannot be more than one funnel plot to assess the publication bias for one meta-analysis. Could you please elaborate more?

Response: We had eight funnel plots for each forest plot drawn to analyze primary outcomes (Line 248)

In Tables 2/3/4, I2 for heterogeneity appears as a decimal value. Is this a mistake? According to the Cochrane Handbook, I2 should be 0-100% as a percentage.

Response: Thank you. We agree. We have changed the I2 decimal to % value throughout the manuscript.

Line 260: cesarean section, which is abbreviated as LSCS. Please correct.

Response: We removed the abbreviation

Suggest American English terms like labor, not 'labour' throughout the manuscript.

Response: We changed to 'labor' throughout the manuscript.

Table 4: 6th column – please explain what you mean by the test for subgroup difference.

Response: Statistically significant subgroup difference is trial / patient characteristic/covariate considered in the subgroup analysis modifies the outcome significantly. P value from the test for subgroup difference is used to assess statistically significant subgroup differences. Usually, P<0.1 indicates a statistically significant subgroup difference (Line 273-276)

Discussion:

The first paragraph needs to be rewritten for clarity. It should start with the research gap and objective and end with the main findings.

Response – Thank you for the guidance. The first paragraph was rewritten to reflect the suggested outline (lines 328 - 342). The second paragraph summarizes the main results (343 – 361).

Please divide the entire discussion into separate sections as sub-topics to increase the readability of the paper. Please follow the steps of a well-written systematic review publication in a reputed journal. For example: Main findings, Critical review of literature, Strengths and limitations, Conclusions, Recommendations, Future directions etc.

Response – Thank you. We have subdivided the discussion into subheadings as suggested.

Line 312: Define ICU/SCBU abbreviations

Response – expanded into words (Lines 376-377)

Reference list:

None of the references have included the journal name.

Response: We have added the journal name to each reference.

We thank both reviewers for appreciating the scientific merit of our submission and encouraging comments made. We sincerely appreciate both reviewers for their time and expertise granted in the comments suggesting vital improvements toward a publication. We have made the necessary amendments and hope the article now meets the expectations for publication.

Attachment

Submitted filename: Response to Reviewers.docx

pone.0298852.s016.docx (33.6KB, docx)

Decision Letter 1

Tanya Doherty

18 Jun 2024

PONE-D-24-02940R1Impact of continuous laborcompanion- who is the best: A systematic review and meta-analysis of randomized controlled trials.PLOS ONE

Dear Dr. Jayasundara,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

The reviewers have recommended minor revisions to your article. Kindly address these before a final decision can be made.

Please submit your revised manuscript by Aug 02 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

  • A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.

  • A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.

  • An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Tanya Doherty, PhD

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

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Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

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Reviewer #1: Yes

Reviewer #2: Yes

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: I Don't Know

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Thank you for the opportunity to review the revised version of the article. I think that the discussion section is much improved and that the article is ready for publication.

One small suggestion to potentially consider is to perhaps unravel some of the complexity relating to the issue of training and familiarity in the paragraph: 'Training of labor companions versus making trained labor companions familiar'. I thought it might be helpful to state explicitly that we aren't sure if the importance of familiarity is much more significant than the training labour companions receive and that familiar companions tend not to have received any training or whether the training being provided is somehow reducing the effectiveness of labour companions who would otherwise be more effective? And the more work needs to be done to understand this relationship?

Reviewer #2: ​Thank you for addressing the reviewer's comments. The manuscript is now very much improved and almost suitable for publication in this journal. However, I would like to suggest a few points. Once these have been addressed, it should be suitable for publication following the editorial review.

- Line 310: I2 is expressed​ as 0.44. Please check.

- Please define all abbreviations used in all tables and figures (such as RR, CI, RCT) at the bottom as footnotes.

- Line 305: You may discuss this finding (length of labor) in the discussion section, probably due to the probable rise of cesarean section rates after 2000.

- Another limitation is the methodological quality of the randomized trials before 2000. There was a huge improvement after 2000, especially with the introduction of trial registries in 2006. These aspects are now being discussed everywhere.

- I noticed a high risk of bias due to blinding: suggest a sentence in the limitations section/discussion section, as blinding is not possible due to the nature of the intervention concerned.

- Please acknowledge the use of the older version - 'original version of the Cochrane risk of bias tool'​, rather than the currently accepted RoB-02 tool. This is an important limitation. You may also replace the word 'RoB - 01' with the name of 'original version of the Cochrane risk of bias tool'​.

- Finally, if the authors are happy (optional request), they can attach the Excel files/summary data files showing the results of the data extraction used to calculate the relative risks for at least the primary outcomes. These can be added as supplementary files. This might enhance the quality of your work.

Congratulations on the good work.

Thank you

**********

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Reviewer #1: No

Reviewer #2: No

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PLoS One. 2024 Jul 23;19(7):e0298852. doi: 10.1371/journal.pone.0298852.r004

Author response to Decision Letter 1

30 Jun 2024

Comments to the Author

Reviewer #1: Thank you for the opportunity to review the revised version of the article. I think that the discussion section is much improved and that the article is ready for publication.

Thank you for the encouraging comments

Reviewer #1: One small suggestion to potentially consider is to perhaps unravel some of the complexity relating to the issue of training and familiarity in the paragraph: 'Training of labor companions versus making trained labor companions familiar'. I thought it might be helpful to state explicitly that we aren't sure if the importance of familiarity is much more significant than the training labour companions receive and that familiar companions tend not to have received any training or whether the training being provided is somehow reducing the effectiveness of labour companions who would otherwise be more effective? And the more work needs to be done to understand this relationship?

We thank the reviewer for the encouraging comments and agree to add clarifications and comments. We have included a brief discussion as suggested. (Lines 428-455)

Reviewer #2: Thank you for addressing the reviewer's comments. The manuscript is now very much improved and almost suitable for publication in this journal. However, I would like to suggest a few points. Once these have been addressed, it should be suitable for publication following the editorial review.

- Line 310: I2 is expressed as 0.44. Please check.

Response: We thank the reviewer for the encouraging evaluation and the suggestions for improvement. We have corrected it as a percentage. (Line 311)

- Please define all abbreviations used in all tables and figures (such as RR, CI, RCT) at the bottom

as footnotes.

Thank you. We have defined it as suggested in the included footnotes.

- Line 305: You may discuss this finding (length of labor) in the discussion section, probably due

to the probable rise of cesarean section rates after 2000.

Thank you. We agree. We have included the discussion (Lines 476-480)

- Another limitation is the methodological quality of the randomized trials before 2000. There

was a huge improvement after 2000, especially with the introduction of trial registries in 2006.

These aspects are now being discussed everywhere.

Thank you. We have included the discussion point (Lines 476-480)

- I noticed a high risk of bias due to blinding: suggest a sentence in the limitations section/

discussion section, as blinding is not possible due to the nature of the intervention concerned.

Thank you. We have included a sentence acknowledging the limitation (Lines 518-521)

- Please acknowledge the use of the older version - 'original version of the Cochrane risk of bias

tool’, rather than the currently accepted RoB-02 tool. This is an important limitation. You may also replace the word 'RoB - 01' with the name of 'original version of the Cochrane risk of bias tool’.

Thank you. We have acknowledged the limitation (Lines 30, 154,156, 250, 520-521)

- Finally, if the authors are happy (optional request), they can attach the Excel files/summary data

files showing the results of the data extraction used to calculate the relative risks for at least the primary outcomes. These can be added as supplementary files. This might enhance the quality of your work.

Response: We are happy to share summary data showing the data extraction results. We have attached summary data as supplementary file 12 (S12 File).

Congratulations on the good work.

Thank you.

Attachment

Submitted filename: Response to Reviewers.docx

pone.0298852.s017.docx (20.1KB, docx)

Decision Letter 2

Tanya Doherty

9 Jul 2024

Impact of continuous laborcompanion- who is the best: A systematic review and meta-analysis of randomized controlled trials.

PONE-D-24-02940R2

Dear Dr. Jayasundara,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Tanya Doherty, PhD

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Acceptance letter

Tanya Doherty

12 Jul 2024

PONE-D-24-02940R2

PLOS ONE

Dear Dr. Jayasundara,

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now being handed over to our production team.

At this stage, our production department will prepare your paper for publication. This includes ensuring the following:

* All references, tables, and figures are properly cited

* All relevant supporting information is included in the manuscript submission,

* There are no issues that prevent the paper from being properly typeset

If revisions are needed, the production department will contact you directly to resolve them. If no revisions are needed, you will receive an email when the publication date has been set. At this time, we do not offer pre-publication proofs to authors during production of the accepted work. Please keep in mind that we are working through a large volume of accepted articles, so please give us a few weeks to review your paper and let you know the next and final steps.

Lastly, if your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

If we can help with anything else, please email us at customercare@plos.org.

Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Professor Tanya Doherty

Academic Editor

PLOS ONE

Associated Data

    This section collects any data citations, data availability statements, or supplementary materials included in this article.

    Supplementary Materials

    S1 Table. Effectiveness of trained versus untrained labor companion.

    (DOCX)

    pone.0298852.s001.docx (13.1KB, docx)
    S2 Table. Effectiveness of a labor companion before and after 2000.

    (DOCX)

    pone.0298852.s002.docx (13KB, docx)
    S1 File. Analysis of spontaneous vaginal delivery.

    (DOCX)

    pone.0298852.s003.docx (139.3KB, docx)
    S2 File. Analysis of duration of labor.

    (DOCX)

    pone.0298852.s004.docx (132.9KB, docx)
    S3 File. Analysis of cesarean section.

    (DOCX)

    pone.0298852.s005.docx (154KB, docx)
    S4 File. Analysis of instrumental delivery.

    (DOCX)

    pone.0298852.s006.docx (144.2KB, docx)
    S5 File. Analysis of oxytocin for labor induction.

    (DOCX)

    pone.0298852.s007.docx (148.8KB, docx)
    S6 File. Analysis of analgesic usage.

    (DOCX)

    pone.0298852.s008.docx (134KB, docx)
    S7 File. Analysis of tocophobia.

    (DOCX)

    pone.0298852.s009.docx (115.7KB, docx)
    S8 File. Analysis of 5 min Apgart < 7.

    (DOCX)

    pone.0298852.s010.docx (104.5KB, docx)
    S9 File. PRISMA 2020 checklist.

    (DOCX)

    pone.0298852.s011.docx (27.5KB, docx)
    S10 File. Detailed search strategy.

    (DOCX)

    pone.0298852.s012.docx (18.8KB, docx)
    S11 File. Study protocol.

    (PDF)

    pone.0298852.s013.pdf (144KB, pdf)
    S12 File. Summary data.

    (DOCX)

    pone.0298852.s014.docx (36.5KB, docx)
    Attachment

    Submitted filename: PLOS ONE Review March 25 2024.docx

    pone.0298852.s015.docx (20.2KB, docx)
    Attachment

    Submitted filename: Response to Reviewers.docx

    pone.0298852.s016.docx (33.6KB, docx)
    Attachment

    Submitted filename: Response to Reviewers.docx

    pone.0298852.s017.docx (20.1KB, docx)

    Data Availability Statement

    All relevant data are within the manuscript and its Supporting Information files.

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