Elsevier

The Lancet

Volume 385, Issue 9987, 27 June–3 July 2015, Pages 2600-2605
The Lancet

Articles
Induction of labour versus expectant management for large-for-date fetuses: a randomised controlled trial

https://doi.org/10.1016/S0140-6736(14)61904-8Get rights and content

Summary

Background

Macrosomic fetuses are at increased risk of shoulder dystocia. We aimed to compare induction of labour with expectant management for large-for-date fetuses for prevention of shoulder dystocia and other neonatal and maternal morbidity associated with macrosomia.

Methods

We did this pragmatic, randomised controlled trial between Oct 1, 2002, and Jan 1, 2009, in 19 tertiary-care centres in France, Switzerland, and Belgium. Women with singleton fetuses whose estimated weight exceeded the 95th percentile, were randomly assigned (1:1), via computer-generated permuted-block randomisation (block size of four to eight) to receive induction of labour within 3 days between 37+0 weeks and 38+6 weeks of gestation, or expectant management. Randomisation was stratified by centre. Participants and caregivers were not masked to group assignment. Our primary outcome was a composite of clinically significant shoulder dystocia, fracture of the clavicle, brachial plexus injury, intracranial haemorrhage, or death. We did analyses by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00190320.

Findings

We randomly assigned 409 women to the induction group and 413 women to the expectant management group, of whom 407 women and 411 women, respectively, were included in the final analysis. Mean birthweight was 3831 g (SD 324) in the induction group and 4118 g (392) in the expectant group. Induction of labour significantly reduced the risk of shoulder dystocia or associated morbidity (n=8) compared with expectant management (n=25; relative risk [RR] 0·32, 95% CI 0·15–0·71; p=0·004). We recorded no brachial plexus injuries, intracranial haemorrhages, or perinatal deaths. The likelihood of spontaneous vaginal delivery was higher in women in the induction group than in those in the expectant management group (RR 1·14, 95% CI 1·01–1·29). Caesarean delivery and neonatal morbidity did not differ significantly between the groups.

Interpretation

Induction of labour for suspected large-for-date fetuses is associated with a reduced risk of shoulder dystocia and associated morbidity compared with expectant management. Induction of labour does not increase the risk of caesarean delivery and improves the likelihood of spontaneous vaginal delivery. These benefits should be balanced with the effects of early-term induction of labour.

Funding

Assistance Publique–Hôpitaux de Paris and the University of Geneva.

Introduction

Macrosomia is a risk factor for unfavourable delivery outcomes, including operative vaginal or caesarean delivery and shoulder dystocia.1, 2 Shoulder dystocia can cause neonatal morbidity, including fracture of the clavicle, brachial plexus injury, or asphyxia. Elective caesarean section can be done to avoid a vaginal delivery complicated by macrosomia. However, findings from a decision analysis3 suggested that the number of elective caesarean sections needed to avoid one permanent brachial plexus injury is quite high. This strategy is thus recommended only when fetal weight is estimated to exceed 4500 g for women with diabetes and 5000 g for those without diabetes.4

Another option would be to induce labour, which reduces the opportunity for continued fetal growth and, theoretically, decreases the risk of caesarean section for cephalopelvic disproportion, and reduces the risk of operative vaginal delivery, perineal trauma, and shoulder dystocia. Nonetheless, induction of labour can fail, which would make caesarean delivery necessary. Early-term (37–38 weeks) delivery, especially by elective caesarean section, might also increase the risk of mortality and morbidity of the neonate, including long-term development issues.5, 6

Several investigators have raised questions about induction of labour for macrosomic fetuses, especially because most observational studies have associated this strategy with an increased risk of caesarean delivery, with no significant decrease in shoulder dystocia.7 A systematic review,8 which included the few randomised trials published,9, 10 showed no difference in the risk of caesarean section between the labour induction and expectant management groups, but also no benefit of labour induction in prevention of neonatal trauma. The conclusions were limited by the relatively small sample size of the trials and by the inclusion of women, usually at 40 weeks of gestation or more, carrying a fetus with an estimated weight of more than 4000 g. Inclusion of these women is likely to restrict the benefit of induction of labour, because this intervention at that stage of gestation leads to very small differences between induced labour and expectant management groups, in both mean gestational age at birth and birthweight.

We assessed the risks and benefits of induction of labour compared with expectant management in women with large-for-date fetuses. We postulated that induction of labour would prevent shoulder dystocia and other neonatal and maternal morbidity associated with macrosomia, with no major changes in the risk of caesarean section.

Section snippets

Study design and participants

We did this multicentre, randomised controlled trial in 19 tertiary-care university hospitals in France, Switzerland, and Belgium. Recruitment started on Oct 1, 2002, in four hospitals and was extended to France in 2005, which added 15 more hospitals. Recruitment ended on Jan 1, 2009.

Eligible women had a singleton macrosomic fetus in cephalic presentation and no contraindications to planned vaginal delivery. We identified the women in two stages, between 36 weeks and 38 weeks of gestation,

Results

The figure shows the trial profile. We randomly assigned 822 women to the induction of labour group (n=409) or the expectant management group (n=413). Four (1%) women were lost to follow-up before delivery, leaving 818 women in the final analysis. Labour was induced in 366 (89%) women in the induction group and 116 (28%) women in the expectant management group (figure). Baseline characteristics were similar between groups (table 1). Mean birthweight was 3831 g (324) in the induction group and

Discussion

Our findings show that induction of labour for large-for-date fetuses significantly reduces the risks of shoulder dystocia and bone fracture, and increases the likelihood of spontaneous vaginal delivery. We recorded no brachial plexus injuries, intracranial haemorrhages, or perinatal deaths, nor did we detect differences between the groups for markers of asphyxia at birth.

Our results differ from those of a systematic review,7 which reported an increased risk of caesarean delivery with no

References (25)

  • DJ Rouse et al.

    The effectiveness and costs of elective cesarean delivery for fetal macrosomia diagnosed by ultrasound

    JAMA

    (1996)
  • Number 40, November 2002

    Obstet Gynecol

    (2002)
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