BMJ  2004;328:314 (7 February), doi:10.1136/bmj.37963.606412.EE (published 26 January 2004)

Paper

Randomised controlled trial of labouring in water compared with standard of augmentation for management of dystocia in first stage of labour

¹ Nightingale Building (67), University of Southampton, Southampton SO17 1BJ, ² Medical Statistics Group, Health Care Research Unit (805), Southampton General Hospital, Southampton SO16 6YD, ³ Trust Management Office (Mail point 18), Southampton General Hospital

Abstract

Objectives To evaluate the impact of labouring in water during first stage of labour on rates of epidural analgesia and operative delivery in nulliparous women with dystocia.

Design Randomised controlled trial.

Setting University teaching hospital in southern England.

Participants 99 nulliparous women with dystocia (cervical dilation rate < 1 cm/hour in active labour) at low risk of complications.

Interventions Immersion in water in birth pool or standard augmentation for dystocia (amniotomy and intravenous oxytocin).

Main outcome measures Primary: epidural analgesia and operative delivery rates. Secondary: augmentation rates with amniotomy and oxytocin, length of labour, maternal and neonatal morbidity including infections, maternal pain score, and maternal satisfaction with care.

Results Women randomised to immersion in water had a lower rate of epidural analgesia than women allocated to augmentation (47% v 66%, relative risk 0.71 (95% confidence interval 0.49 to 1.01), number needed to treat for benefit (NNT) 5). They showed no difference in rates of operative delivery (49% v 50%, 0.98 (0.65 to 1.47), NNT 98), but significantly fewer received augmentation (71% v 96%, 0.74 (0.59 to 0.88), NNT 4) or any form of obstetric intervention (amniotomy, oxytocin, epidural, or operative delivery) (80% v 98%, 0.81 (0.67 to 0.92), NNT 5). More neonates of women in the water group were admitted to the neonatal unit (6 v 0, P = 0.013), but there was no difference in Apgar score, infection rates, or umbilical cord pH.

Conclusions Labouring in water under midwifery care may be an option for slow progress in labour, reducing the need for obstetric intervention and offering an alternative pain management strategy.

Introduction

Management strategies for slower than expected progress in the first stage of labour (dystocia) vary from immediate augmentation^{1 2} to delayed intervention up to four hours after diagnosis.^3-5 Comparison between strategies is difficult as specific features often differ. Our current trial was based on two precepts. Firstly, that incomplete understanding of labour may lead to unnecessarily early intervention. Secondly, that anxiety and pain may trigger a stress response,⁶ leading to reduced uterine activity and dystocia.⁷ Labouring in water may ameliorate this stress response by aiding relaxation and pain relief. A Cochrane review concluded that, for women at low risk of complications, there was no clear evidence of advantage or disadvantage in using a pool in labour but further research was needed.⁸ Two national surveys concluded that labour and birth in water had no effect on perinatal mortality.^{9 10}

Our current trial compares labour in water with augmentation in nulliparous women with dystocia.

Participants and methods

Design
Our randomised controlled trial compared immersion in water during the first stage of labour after diagnosis of dystocia with augmentation, the standard management for dystocia. We conducted the trial between January 1999 and December 2000 in a university teaching hospital with about 4500 births a year.

Study population
Nulliparous women with a diagnosis of dystocia (cervical dilation of < 1 cm/hour)—who at that time would routinely have been advised to have their labour augmented by amniotomy or oxytocin injection, or both—were eligible for the trial if they were able to give informed consent, had received information about the trial during their pregnancy (a leaflet describing the trial was distributed to all nulliparous women antenatally), were in spontaneous, active labour, and were at low risk of complications (full term, singleton pregnancies, fetus in cephalic presentation, and no medical, obstetric, or psychiatric problems).

Intervention
After participating women were randomised, each management option consisted of a package of care provided by midwives, including one to one care. Labour progress was assessed by vaginal examinations every four hours and documented on a standard partogram. All women could request any form of analgesia available at any time.

Augmentation—This group received the standard management for dystocia. Amniotomy was performed if the membranes were intact, and a midwife managed the labour for the next two hours unless otherwise clinically indicated. If the membranes were already ruptured or progress was not satisfactory during the two hours after amniotomy, intravenous oxytocin was given until regular contractions occurred. Continuous fetal monitoring was carried out.

Labour in water—This group used a permanent waterbirth pool filled with tap water without additives so that immersion was to above the breasts when sitting. Water temperature was maintained at 36.0-37.0°C. The maximum stay in the pool before reassessment by vaginal examination was four hours. If labour progress was satisfactory (cervical dilation 1 cm/hour), subsequent care could continue in the pool if the woman wished, otherwise augmentation was advised.

Sample size
We based our estimate of the potential effect size on an audit of 50 nulliparous women with dystocia in May-July 1997, who would have met the trial inclusion criteria. We concluded that 220 women would be required to detect an absolute reduction of 25% in the rate of epidural analgesia (from 60% to 35%) and an absolute reduction of 20% in the operative delivery rate (from 40% to 20%) with 90% power in 5% two sided tests. We planned a recruitment period of two years.

After dystocia was diagnosed in an eligible woman, she was randomly allocated to a treatment arm using allocation details concealed in consecutively numbered envelopes.

Outcome measures
Primary outcome measures were epidural analgesia and operative delivery. Secondary measures included augmentation rates and maternal or neonatal morbidity (any infection, admission to the neonatal unit, or condition that required medical care up to the 10th postpartum day). It was not possible to conceal allocation from clinical practitioners. However, as data were objective in nature and recorded contemporaneously, observer bias was minimised.

We conducted a postpartum structured interview in the maternity unit to assess retrospectively the women's experience of pain at 30 minutes after the intervention started and change in pain over the same time period. We did not assess pain concurrently because of the disruption to the women and midwives. We also assessed women's satisfaction overall and in relation to privacy and freedom of movement. We used a structured interview format to reduce potential bias.

Statistical analysis
We compared rates of epidural analgesia and operative delivery between groups. We produced numbers needed to treat to produce benefit in one woman and calculated confidence intervals. We compared length of labour and women's pain and satisfaction scores.

Results

Recruitment
Of 3825 nulliparous women who delivered in the unit during the two years of recruitment, 741 were defined as being at low risk of complications at the time of the diagnosis of dystocia. Consent was sought from 176 eligible women, of whom 99 (56%) agreed to participate, and were randomised. The two groups of women showed no important differences in baseline characteristics. Forty eight of the 49 women allocated to labour in water used the pool, and 48 of the 50 women allocated to standard care received augmentation.

Primary outcomes
Twenty three women (47%) allocated to labour in water received epidural analgesia after randomisation compared with 33 (66%) in the augmentation group (table 1). The numbers of operative deliveries were similar in both arms of the trial.

View this table: [in this window] [in a new window]   Table 1 Epidural analgesia, mode of delivery, and secondary outcomes among nulliparous women with dystocia allocated to labour in a birth pool or standard augmentation (amniotomy and intravenous oxytocin). Values are numbers (percentages) of women unless otherwise indicated

 

Secondary outcomes
Twenty five of the 27 women in the water labour arm who had made slow progress at the assessment four hours after recruitment received augmentation. A further three women progressed slowly subsequently and also received augmentation. Seven women who progressed satisfactorily received an amniotomy for other indications. The number of women who received augmentation in the water labour arm was significantly lower than that in the standard care arm (table 1).

The mean duration of the first stage of labour was similar in the two groups, (table 2). Women allocated to labour in water reported significantly lower mean pain scores at 30 minutes after start of the allocated management and a reduction in mean pain compared with an increase for women receiving augmentation. Women allocated to labour in water were more likely to report satisfaction with freedom of movement and with experience of privacy, but there was no difference between groups in overall satisfaction (table 2).

View this table: [in this window] [in a new window]   Table 2 Labour length and retrospectively reported pain and satisfaction among nulliparous women with dystocia allocated to labour in a birth pool or standard augmentation (amniotomy and intravenous oxytocin). Values are numbers (percentages) of women unless otherwise indicated

 

Maternal and neonatal wellbeing
Maternal and neonatal infection rates were similar in the two groups, as was neonatal condition at birth indicated by Apgar score and umbilical cord pH. Six neonates born to women in the water labour group were admitted to the neonatal unit compared with none in the augmentation group (P = 0.013). The reasons for admission were: cardiac defects (1), hypothermia (2), fever (1), suspected infection on day 2 (1), and poor feeding on day 3 (1). There was a mean delay of 6 hours (range 2-10 hours) between women leaving the pool and birth. Apart from the infant with cardiac defects, the other five neonates who had required an operative delivery were reunited with their mothers within 48 hours and experienced no subsequent problems.

Discussion

This is the first trial to evaluate the impact of labouring in water for nulliparous women with dystocia. Compared with women given standard augmentation, the women labouring in water had no difference in operative delivery rates and tended to receive less epidural analgesia. Almost 30% of women in the water arm did not receive augmentation and 20% received no obstetric intervention, without evidence of longer labour, both of these rates being significantly different from the augmentation arm. In addition, women retrospectively reported less pain and increased satisfaction.

A management approach that reduces rates of augmentation and associated obstetric intervention may contribute positively to maternal physiological and psychological health: oxytocin infusion is known to increase the risk of uterine hyperstimulation and fetal hypoxia, and obstetric interventions are associated with lower maternal satisfaction.¹¹ A reduced need for epidural analgesia and augmentation may enable staff and other resources to be used differently—for example, allowing more women to receive one to one care in labour.

Maternal and neonatal wellbeing
The trial was not large enough to detect differences in maternal and fetal morbidity. However, indicators of wellbeing were similar in the two groups, with the exception of increased admission to the neonatal unit after labour in water. Possible reasons for this include the water immersion itself, the delay in intervention of up to four hours (even though this did not effect overall labour length), extra caution by practitioners when women were known to have laboured in water, or chance factors with no direct relation to the trial. No other studies of labour in water have reported such an association: instead, they either did not provide data on admissions to neonatal units^{12 13} or reported only one admission¹⁴ or similar admission rates in both trial arms.¹⁵ Eckert et al reported an increased incidence of initial resuscitation measures with water immersion,¹⁵ but we found no difference in Apgar scores and blood gas analysis at birth. Indeed, three of the admissions to the neonatal unit were between nine and 48 hours after delivery, while the three admissions immediately after birth were associated with temperature regulation. Comparative studies of labour in water found no increase in admissions to neonatal units or other markers of neonatal distress.^16-18

Limitations of study
Only 99 of the intended 220 women were recruited for a variety of reasons. Epidural analgesia was the main reason why nulliparous women were ineligible for our study (28%). In our busy maternity unit recruitment was not a priority, and some eligible women were not invited to participate. The main reason eligible women chose not to enter the trial was a preference for one or other form of care (40%). Consideration is needed on how this may affect the generalisability of our findings and recruitment problems.

Recruitment became more difficult towards the end of the trial because of the adoption of a more conservative approach to managing dystocia in the unit and the introduction of the modified World Health Organization partogram,³ which incorporates a delay between the identification of slow progress and augmentation. During this delay midwives could facilitate ongoing conservative management; as a consequence, they were less willing to recruit women to the trial, knowing that half of the women would immediately receive augmentation. The low recruitment rate contributed to the outcomes achieved, such as the lack of statistical significance in relation to the difference in rates of epidural analgesia.

What is already known For women in normal labour, immersion in water is associated with less need for analgesia and increased satisfaction Augmentation of labour, in particular oxytocin administration, is associated with hyperstimulation and decreased maternal satisfaction What this study adds For nulliparous women with dystocia (cervical dilation < 1 cm/hour), immersion in water for up to four hours seemed to reduce need for augmentation of labour, reduce pain, and increase satisfaction, without increasing overall length of labour or operative delivery rate Water immersion may be an alternative option to early augmentation of labour

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This is the abridged version of an article that was posted on bmj.com on 26 January 2004: http://bmj.com/cgi/doi/10.1136/bmj.37963.606412.EE

We thank the women who participated in the trial; the midwives and obstetric and support staff of the unit where the trial was conducted; research advisory group members Maggie Elliot and Debbie Gould; and Rona McCandlish for her support in preparing this paper.

Contributors: See bmj.com

Funding: Southampton University Hospitals NHS Trust.

Competing interest: None declared.

Ethical approval: Approval was given by the local research ethics committee.

References

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8. Nikodem VC. Immersion in water during pregnancy, labour and birth. In: Cochrane Library. Issue 1. Oxford: Update Software, 2003.
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(Accepted 18 November 2003)

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