The Timing of Elective Caesarean Deliveries and Early Neonatal Outcomes in Singleton Infants Born at 37 to 41 Weeks’ Gestation

Abstract

The rate of scheduled cesarean delivery (CD) rates has increased (eg, elective repeated CDs), and the impact on neonatal outcomes depends on the gestational age (GA) when they are performed. The risk for adverse neonatal outcomes with increasing GA continues to decrease until 39 weeks of gestation. Guidelines now recommend delaying scheduled CD in low-risk pregnancies until at least 39 weeks and classifying early term (ET) as 37 to 38+6 weeks, full term (FT) as 39 to 40 weeks, and late term (LT) as 41 to 41+6 weeks. This retrospective cohort study was undertaken to assess the effect of timing of scheduled CD at term on early neonatal outcomes. Short-term neonatal outcomes were determined for singleton babies born by elective CD at 37 to 41 completed weeks of gestation between 1998 and 2009. Data on maternal demographic, pregnancy, and neonatal birth characteristics were extracted from institutional databases. The primary outcome was serious respiratory morbidity, defined as admission to the neonatal critical care unit (NCCU) with respiratory morbidity and receiving assisted ventilation via mechanical ventilation or continuous positive airway pressure for 4 hours or longer. Secondary outcomes included neonatal death, low Apgar score, resuscitation, depression at birth, hypoxic ischemic encephalopathy, admission to the NCCU for 1 or more days and 5 or more days, jaundice requiring phototherapy, hypoglycemia, any oxygen in the NCCU or assisted ventilation, respiratory outcomes, small for GA (SGA), and large for GA (LGA). The ET (37–38+6) group was compared with the reference group of full- and late-term (FLT) births (FT, 39–40+6, and LT, 41–41+6 weeks). Of 79,120 singleton births, 26,542 (33.5%) were by CD, of which 15,157 (57.1%) were scheduled (deemed elective in this study). After exclusions, the final cohort included 8657 (59.9%) ET and 5790 (40.1%) FLT births. Of ET births, 87.1% (7544) were at 38 completed weeks; for FLT, 93.6% were FT (85.9% at 39 weeks). In both groups, the most common indication for elective CD was previous CD. The primary outcome of serious respiratory morbidity occurred in 0.5% and 1.2% of FLT and ET babies, respectively (P Early term delivery at least doubled the risk for most outcomes, and outcomes continued to improve with increasing GA, up to 41 weeks. These results support recommendations to delay elective CD deliveries until week 39, although prospective studies are needed to assess the risk for delaying delivery and to examine the long-term and economic impact of elective CD deliveries.