Timing of Elective Repeat Cesarean Delivery at Term and Neonatal Outcomes

The risk of neonatal adverse respiratory outcomes is higher among infants delivered before 39 weeks’ gestation than after 39 weeks’, and among infants delivered by prelabor cesarean compared to those delivered vaginally. Thus, elective cesarean section before 39 weeks is discouraged in the absence of fetal lung maturity. This prospective study compared neonatal outcomes among infants delivered by elective cesarean delivery at 37, 38, and 39 weeks’ gestation. The study cohort was pregnant women with viable singleton pregnancies undergoing repeat cesarean delivery at 19 academic medical centers. The women were delivered before onset of labor and had no medical or obstetrical indications for delivery before 39 weeks. The primary study outcome was a composite of any adverse neonatal outcome or death. Adverse outcomes included respiratory complications, admission to the neonatal intensive care unit (ICU), newborn sepsis, treated hypoglycemia, and hospitalization for 5 days or longer. Logistic regression models were used to calculate adjusted odds ratios for the association between neonatal outcomes and gestational age at birth relative to 39 completed weeks. Among the study cohort, 13,258 women underwent elective repeat cesarean section at term. Of these, 49.1% had the procedure at 39 weeks’, and 35.8% had the procedure before 39 completed weeks’ gestation (6.3% at 37 weeks and 29.5% at 38 weeks). With increasing gestational age at birth, the risk of the primary outcome decreased. Unadjusted analysis showed that the incidence of the primary outcome was 15.3% at 37 weeks, 11.0% at 38 weeks, and 8.0% at 39 weeks (P for trend <0.001). The differences remained after adjusting for variables (P for trend <0.001). The adjusted risk of individual adverse outcomes including adverse respiratory complications, admission to the neonatal ICU, newborn sepsis, hypoglycemia, admission to the neonatal ICU, and hospitalization for 5 days or more were increased by a factor of 1.8 to 4.2 for births at 37 weeks and 1.3 to 2.1 for births at 38 weeks, relative to births at 39 weeks’ gestation. There was only 1 neonatal death, of an infant born at 39 weeks. These findings suggest that postponing elective delivery to 39 weeks might prevent a significant number of adverse neonatal outcomes or deaths, and support recommendations to delay elective delivery until 39 weeks’ gestation.