Maternal and Newborn Outcomes with Elective Induction of Labor at Term

Abstract Background A growing body of evidence supports improved or not worsened birth outcomes with non-medically indicated induction of labor at 39 weeks compared to expectant management. This evidence includes two recent randomized control trials. However, concern has been raised as to whether these studies are applicable to a broader US pregnant population. Objective Our goal was to compare outcomes for electively induced births at 39 weeks or beyond with those that were not electively induced. Study Design Retrospective cohort study using chart-abstracted data on births from January 1, 2012 - December 31, 2017 at 21 hospitals in the Northwest US. The study was restricted to singleton cephalic hospital births at 39 +0 –42 +6 weeks. Exclusions included previous cesarean, missing data for delivery type or gestational week at birth, antepartum stillbirth, cesarean without any attempt at vaginal birth, fetal anomaly, gestational diabetes, pre-pregnancy diabetes, and pre-pregnancy hypertension. The rate of cesarean birth for elective inductions at both 39 weeks and 40 weeks was compared to the rate in all other on-going pregnancies in the same gestational week. Maternal outcomes (operative vaginal birth, shoulder dystocia, 3rd or 4th degree perineal laceration, pregnancy related hypertension, and postpartum hemorrhage) and newborn outcomes (macrosomia, 5-minute Apgar Results A total of 55,694 births were included in the study cohort: 4002 elective inductions at > 39 +0 weeks and 51,692 births at 39 +0 -42 +6 weeks that were not electively induced. In nulliparous women, elective induction at 39 weeks was associated with a decreased likelihood of cesarean birth (14.7% versus 23.2%; aOR 0.61; 95% CI 0.41-0.89) and an increased rate of operative vaginal birth (18.5% versus 10.8%; aOR 1.8; 95% CI 1.28-2.54) compared to ongoing pregnancies. In multiparous women, cesarean birth rates were similar in the elective inductions and on-going pregnancies. Elective induction at 39 weeks was associated with a decreased likelihood of pregnancy related hypertension in nulliparous (2.2% versus 7.3%; aOR 0.28; 95% CI 0.11-0.68) and multiparous women (0.9% versus 3.5%; aOR 0.24; 95% CI 0.15-0.38). Term elective induction was not associated with any statistically significant increase in adverse newborn outcomes. Elective induction of labor at 39 weeks was associated with increased time from admission to delivery for both nulliparous (1.3 hours; 95% CI 0.2-2.3) and multiparous women (3.4 hours; 95% CI 3.2-3.6). Conclusion Elective induction of labor at 39 weeks is associated with a decrease in cesarean birth in nulliparous women , decreased pregnancy related hypertension in multiparous and nulliparous women, and increased time on labor and delivery. How to use this information remains the challenge.