Induction of labour at or beyond 37 weeks' gestation.
Risks of stillbirth or neonatal death increase as gestation continues beyond term (around 40 weeks' gestation). It is unclear whether a policy of labour induction can reduce these risks. This Cochrane Review is an update of a review that was originally published in 2006 and subsequently updated in 2012 and 2018.
To assess the effects of a policy of labour induction at or beyond 37 weeks' gestation compared with a policy of awaiting spontaneous labour indefinitely (or until a later gestational age, or until a maternal or fetal indication for induction of labour arises) on pregnancy outcomes for the infant and the mother.
For this update, we searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) (17 July 2019), and reference lists of retrieved studies.
Randomised controlled trials (RCTs) conducted in pregnant women at or beyond 37 weeks, comparing a policy of labour induction with a policy of awaiting spontaneous onset of labour (expectant management). We also included trials published in abstract form only. Cluster-RCTs, quasi-RCTs and trials using a cross-over design were not eligible for inclusion in this review. We included pregnant women at or beyond 37 weeks' gestation. Since risk factors at this stage of pregnancy would normally require intervention, only trials including women at low risk for complications, as defined by trialists, were eligible. The trials of induction of labour in women with prelabour rupture of membranes at or beyond term were not considered in this review but are considered in a separate Cochrane Review.
Two review authors independently assessed trials for inclusion, assessed risk of bias and extracted data. Data were checked for accuracy. We assessed the certainty of evidence using the GRADE approach.
In this updated review, we included 34 RCTs (reporting on over 21,000 women and infants) mostly conducted in high-income settings. The trials compared a policy to induce labour usually after 41 completed weeks of gestation (> 287 days) with waiting for labour to start and/or waiting for a period before inducing labour. The trials were generally at low to moderate risk of bias. Compared with a policy of expectant management, a policy of labour induction was associated with fewer (all-cause) perinatal deaths (risk ratio (RR) 0.31, 95% confidence interval (CI) 0.15 to 0.64; 22 trials, 18,795 infants; high-certainty evidence). There were four perinatal deaths in the labour induction policy group compared with 25 perinatal deaths in the expectant management group. The number needed to treat for an additional beneficial outcome (NNTB) with induction of labour, in order to prevent one perinatal death, was 544 (95% CI 441 to 1042). There were also fewer stillbirths in the induction group (RR 0.30, 95% CI 0.12 to 0.75; 22 trials, 18,795 infants; high-certainty evidence); two in the induction policy group and 16 in the expectant management group. For women in the policy of induction arms of trials, there were probably fewer caesarean sections compared with expectant management (RR 0.90, 95% CI 0.85 to 0.95; 31 trials, 21,030 women; moderate-certainty evidence); and probably little or no difference in operative vaginal births with induction (RR 1.03, 95% CI 0.96 to 1.10; 22 trials, 18,584 women; moderate-certainty evidence). Induction may make little or difference to perineal trauma (severe perineal tear: RR 1.04, 95% CI 0.85 to 1.26; 5 trials; 11,589 women; low-certainty evidence). Induction probably makes little or no difference to postpartum haemorrhage (RR 1.02, 95% CI 0.91 to 1.15, 9 trials; 12,609 women; moderate-certainty evidence), or breastfeeding at discharge (RR 1.00, 95% CI 0.96 to 1.04; 2 trials, 7487 women; moderate-certainty evidence). Very low certainty evidence means that we are uncertain about the effect of induction or expectant management on the length of maternal hospital stay (average mean difference (MD) -0.19 days, 95% CI -0.56 to 0.18; 7 trials; 4120 women; Tau² = 0.20; I² = 94%). Rates of neonatal intensive care unit (NICU) admission were lower (RR 0.88, 95% CI 0.80 to 0.96; 17 trials, 17,826 infants; high-certainty evidence), and probably fewer babies had Apgar scores less than seven at five minutes in the induction groups compared with expectant management (RR 0.73, 95% CI 0.56 to 0.96; 20 trials, 18,345 infants; moderate-certainty evidence). Induction or expectant management may make little or no difference for neonatal encephalopathy (RR 0.69, 95% CI 0.37 to 1.31; 2 trials, 8851 infants; low-certainty evidence, and probably makes little or no difference for neonatal trauma (RR 0.97, 95% CI 0.63 to 1.49; 5 trials, 13,106 infants; moderate-certainty evidence) for induction compared with expectant management. Neurodevelopment at childhood follow-up and postnatal depression were not reported by any trials. In subgroup analyses, no differences were seen for timing of induction (< 40 versus 40-41 versus > 41 weeks' gestation), by parity (primiparous versus multiparous) or state of cervix for any of the main outcomes (perinatal death, stillbirth, NICU admission, caesarean section, operative vaginal birth, or perineal trauma).
There is a clear reduction in perinatal death with a policy of labour induction at or beyond 37 weeks compared with expectant management, though absolute rates are small (0.4 versus 3 deaths per 1000). There were also lower caesarean rates without increasing rates of operative vaginal births and there were fewer NICU admissions with a policy of induction. Most of the important outcomes assessed using GRADE had high- or moderate-certainty ratings. While existing trials have not yet reported on childhood neurodevelopment, this is an important area for future research. The optimal timing of offering induction of labour to women at or beyond 37 weeks' gestation needs further investigation, as does further exploration of risk profiles of women and their values and preferences. Offering women tailored counselling may help them make an informed choice between induction of labour for pregnancies, particularly those continuing beyond 41 weeks - or waiting for labour to start and/or waiting before inducing labour.
Middleton P
，Shepherd E
，Morris J
，Crowther CA
，Gomersall JC
... -
《Cochrane Database of Systematic Reviews》
Association between timing of labor induction and neonatal and maternal outcomes: an observational study from China.
Growing evidence suggests that elective induction of labor at 39 weeks' gestation may lead to more favorable perinatal outcomes than expectant management, however, how to weigh the pros and cons of elective labor induction at 39 weeks, the expectation of spontaneous delivery at 40 or 41 weeks, or delayed labor induction at 40 or 41 weeks on neonatal and maternal outcomes remains a practical challenge in clinical decision-making.
We compared the neonatal and maternal outcomes between elective induction of labor at 39 weeks' gestation and expectant management in a real-world setting. We also divided the expectantly managed group and compared outcomes of the spontaneous delivery at 40 or 41 weeks' gestation group and the induced group at 40 or 41 weeks' gestation with those of the elective induction at 39 weeks' gestation group.
This retrospective cohort study included 21,282 participants who delivered between January 1, 2019, and June 30, 2022. Participants were initially categorized into 3 groups at 39 weeks' gestation, namely elective induction of labor, spontaneous delivery, and expectant management, for the primary analysis in which elective induction was compared with expectant management. Subsequently, the expectant management group at 39 weeks' gestation was divided into 3 groups at 40 weeks, and participants who underwent expectant management at 40 weeks were then divided into 2 groups at 41 weeks' gestation, namely elective induction and spontaneous delivery. In total, 6 groups were compared in the secondary analysis with the elective induction at 39 weeks' gestation group serving as the reference group.
At 39 weeks' gestational age, participants who underwent elective induction of labor had a significantly lower risk for the primary composite outcomes than participants who were managed expectantly (adjusted odds ratio, 0.72; 95% confidence interval, 0.55-0.95), and there was no significant difference in the risk for cesarean delivery between the 2 groups. After further dividing the expectantly managed group and comparing them with participants who underwent elective induction of labor at 39 weeks' gestation, those who underwent spontaneous delivery at 40 weeks' gestation had significantly lower risks for cesarean delivery (0.61; 0.52-0.71) and chorioamnionitis (0.78; 0.61-1.00) but a higher risk for fetal distress (1.39; 1.22-1.57); those with spontaneous delivery at 41 weeks' gestation had a significantly higher risk for fetal distress (1.44; 1.16-1.79), postpartum hemorrhage (1.83; 1.26-2.66), and prolonged or arrested labor (1.61; 1.02-2.54). Moreover, when compared with participants who underwent elective induction of labor at 39 weeks' gestation, participants who were induced later in gestation had significantly higher risks for adverse neonatal and maternal outcomes, especially at 40 weeks' gestation.
Our findings indicate that elective induction of labor at 39 weeks' gestation was significantly associated with lower risks for adverse short-term neonatal and maternal outcomes when compared with expectant management. Moreover, our study highlights the nuanced trade-offs in risks and benefits between elective induction at 39 weeks' gestation and waiting for spontaneous labor or delayed induction at 40 or 41 weeks' gestation, thus providing valuable insights for clinical decision-making in practice.
Hu Y
，Chen B
，Wang X
，Zhu S
，Bao S
，Lu J
，Wang L
，Wang W
，Wu C
，Qi L
，Wang Y
，Li F
，Xie W
，Wu Y
，Hu L
，Xia Y
，Lou B
，Guo R
，Xie B
，Chen X
，Han Y
，Chen D
，Ma H
，Liang Z
... -
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ResearchGate
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