Outcomes of elective induction of labor compared with expectant management: population based study

BMJ 2012;344:e2838

Abstract

Objective To determine neonatal outcomes (perinatal mortality and special care unit admission) and maternal outcomes (mode of delivery, delivery complications) of elective induction of labor compared with expectant management.

Design Retrospective cohort study using an unselected population database.

Setting Consultant and midwife-led obstetric units in Scotland 1981-2007.

Participants 1 271 549 women with singleton pregnancies of 37 weeks or more gestation.

Interventions
Outcomes of elective induction of labor (induction of labor with no recognized medical indication) at 37, 38, 39, 40, and 41 weeks’ gestation compared with those of expectant management (continuation of pregnancy to either spontaneous labor, induction of labor or cesarean section at a later gestation).

Main outcome measures Extended perinatal mortality, mode of delivery, postpartum hemorrhage, obstetric anal sphincter injury, and admission to a neonatal or special care baby unit. Outcomes were adjusted for age at delivery, parity, year of birth, birth weight, deprivation category, and, where appropriate, mode of delivery.

Results
At each gestation between 37 and 41 completed weeks, elective induction of labor was associated with a decreased odds of perinatal mortality compared with expectant management (at 40 weeks’ gestation 0.08% (37/44 764) in the induction of labor group versus 0.18% (627/350 643) in the expectant management group; adjusted odds ratio 0.39, 99% confidence interval 0.24 to 0.63), without a reduction in the odds of spontaneous vertex delivery (at 40 weeks’ gestation 79.9% (35 775/44 778) in the induction of labor group versus 73.7% (258 665/350 791) in the expectant management group; adjusted odds ratio 1.26, 1.22 to 1.31).

Admission to a neonatal unit was, however, increased in association with elective induction of labor at all gestations before 41 weeks (at 40 weeks’ gestation 8.0% (3605/44 778) in the induction of labor group compared with 7.3% (25 572/350 791) in the expectant management group; adjusted odds ratio 1.14, 1.09 to 1.20).

Conclusion
Although residual confounding may remain, our findings indicate that elective induction of labor at term gestation can reduce perinatal mortality in developed countries without increasing the risk of operative delivery.