Induction of labor at the 39th week and cesarean delivery: a retrospective study in a Shanghai-based maternity hospital.

Abstract

This study aimed at exploring the association between labor induction at the 39th week and CD in the setting where the baseline cesarean delivery rate is high. A retrospective cohort study was conducted during a 50-month period at a Shanghai-based secondary maternity hospital. A comparison was made of the maternal and neonatal outcomes, including the CD rate, between the women who underwent labor induction at the 39th week and those who were managed expectantly. A total of 4,975 deliveries were included, which had been made by the low-risk nulliparous women beyond 39 weeks. The CD rate was 41.6% and 42.2% in the induction group (n = 202) and the expectant management group (n = 4,773), respectively (relative risk, 0.99; 95% CI, 0.83 to 1.17). Induction of labor at the 39th week increased the risk of postpartum hemorrhage ≥ 500 ml in 24 hours (adjusted relative risk, 2.32; 95% CI, 1.12 to 4.78) and intrapartum fever ≥ 37.5℃ (adjusted relative risk, 4.73; 95% CI, 2.13 to 10.49). Differences in other maternal and neonatal outcomes were of no clinical significance. When stratified by the indications for labor induction, CDs performed because of non-reassuring fetal heart rate were more prevalent among the women who were induced for the same reason than those who were not. As compared with that in the expectant management, labor induction at the 39th week does not seem to have an impact on CD within the setting of a high CD rate.