This is a plain English summary of an original research article
Inducing labour may halve the risk of infection in the womb when waters break from 37 weeks. The procedure was started within 24 hours and was compared to waiting for labour to start on its own.
Waters breaking at full term without the onset of labour is called pre-labour rupture of membranes. This can increase risks of maternal and neonatal infection and the need for caesarean section. As most women deliver spontaneously within a day, NICE recommend that women are offered an informed choice of either induction 24 hours after premature rupture of membranes or to watch and wait.
This updated Cochrane review included new evidence and suggests that induction before 24 hours may reduce infections without increasing caesarean sections, but there remains some uncertainty. This is due to low study quality, lack of longer term outcomes, and too few participants in trials to compare the numbers of any rare serious events.
These findings may help inform shared decisions about induction by providing more information to help women understand the risks.
Why was this study needed?
Premature rupture of membranes (PROM) at full term (37 weeks or more) occurs in 8% of pregnancies. Spontaneous onset of labour within 24 hours occurs in approximately 95% of cases. Labour can be delayed for up to seven days if it does not start within 24 hours.
The risk of maternal or neonatal infection and the need for caesarean section are increased by PROM. Untreated infections can lead to complications with reproductive organs, problems with fertility and general health.
PROM at term is managed by either by inducing labour quickly (usually the next morning i.e. under 24 hours) or expectant management which involves waiting for labour to begin and induction of labour if it does not occur in a specific period or there are other reasons to intervene.
It is not clear if waiting for birth to occur spontaneously or intervening to induce labour within the first 24 hours has better outcomes for the mother and baby, everything else being equal.
This updated Cochrane review included eight new trials and aimed to compare the effects of each management strategy.
What did this study do?
This systematic review and meta-analysis included 23 randomised controlled trials including 8,615 women at full term that had PROM. Eleven trials were conducted in Europe or US/Canada.
Trials were included if they compared the effects of immediate induction intervention or intervention within 24 hours to no planned intervention within 24 hours (expectant management).
The main outcomes were whether either option was better at reducing the risk of maternal infection in the lining of the uterus (endometritis) and/or the fetal membranes (chorioamnionitis) or the need for caesarean section. Researchers also looked for stillbirths or complications for the baby recorded in the trials.
For some outcomes, the quality of the evidence was downgraded to low due to a high risk of bias and large differences between the studies. However, the maternal infection and caesarean section outcomes are objective so we are moderately confident in these results.
What did it find?
- Low quality evidence from eight trials (6,864 women) found women who had an intervention to induce labour within 24 hours of PROM had a reduced risk of chorioamnionitis and/or endometritis (54 per 1,000) compared to women who had expectant management (110 per 1,000); risk ratio (RR) 0.49, 95% confidence interval (CI) 0.33 to 0.72. Subgroup analyses showed women with a planned induction intervention had a reduced risk of chorioamnionitis (RR 0.55, 95% CI 0.37 to 0.82). There was no difference for endometritis but this was based on one small trial of 86 women from 1989.
- Low quality evidence from 23 trials (8,576 women) found no significant difference in the risk of caesarean section between women with planned interventions to induce labour (126 per 1,000) compared to expectant management (150 per 1,000); RR 0.84, 95% CI 0.69 to 1.04.
- Very low quality evidence from three trials reported no serious maternal outcomes or deaths and therefore found no difference between the intervening to induce labour and expectant management groups. However, stillbirths and maternal deaths are rare outcomes in the UK.
- Low quality evidence from 16 trials (7,314 infants) found women who had an intervention to induce labour had less likelihood of their babies having definite or probable sepsis (30 per 1,000) compared to women who had expectant management (41 per 1,000); RR 0.73, 95% CI 0.58 to 0.92.
- Moderate evidence from eight trials (6,392 infants) found no significant difference in stillbirth or neonatal death for women with a planned intervention (1 per 1,000) compared to expectant management (2 per 1,000); RR 0.47, 95% CI 0.13 to 1.66.
What does current guidance say on this issue?
NICE’s 2008 guidance on induction of labour recommends that women with PROM at or over 37 weeks be offered a choice of induction of labour with vaginal prostaglandin or expectant management. It states that induction of labour is appropriate approximately 24 hours after the rupture of the membranes occurs.
Parts of this 2008 guideline are currently being updated, including the recommended methods for induction of labour. The recommendations stated above on information and advice for women being offered induction of labour are not under review.
What are the implications?
Given the remaining uncertainties highlighted in this review and the fact that most women with PROM will give birth anyway within 24 hour, implications are tentative. No clear recommendations are possible from this review, on which of the different induction techniques including vaginal or oral prostaglandins, intravenous oxytocin, acupuncture and homeopathy are best.
However, for some outcomes there are some risk estimates here that could be helpful for midwives, obstetricians and women seeking to understand the relative risks of these shared decisions. These decisions, of course, cannot be avoided.
Citation and Funding
Middleton P, Shepherd E, Flenady V, et al. Planned early birth versus expectant management (waiting) for prelabour rupture of membranes at term (37 weeks or more). Cochrane Database Syst Rev. 2017(1):CD005302.
This project was funded by the National Institute for Health Research Cochrane Programme Grant project (project number 13/89/05), the NHS Programme for Research & Development, the Australian Research for Health of Women and Babies and the National Health and Medical Research Council in Australia.
NICE. Inducing labour. CG70. London: National Institute for Health and Care Excellence; 2008.
Produced by the University of Southampton and Bazian on behalf of NIHR through the NIHR Dissemination Centre