Risk of neonatal mortality according to gestational age after elective repeat cesarean delivery

Despite the well-known neonatal morbidity risks after elective cesarean deliveries performed before 39 weeks, there are scarce data regarding mortality risks. The objective of this study was to calculate the risk of neonatal mortality after elective repeat cesarean delivery (ERCD) by gestational age.

The Linked Birth-Infant Death Data Files from the Vital Statistics Data of the Center for Disease Control and Prevention of the U.S. from 2004 to 2008 were analyzed. Only ERCD cases were included. Early death (<7 days), neonatal death (<28 days), and infant death (<1 year) were evaluated. A logistic regression model was used to calculate odds ratios. Cases delivered at 37-41 weeks were studied with 40 weeks as reference.

A total of 483,052 cases were included for analysis. The distribution of rates and odds ratios for infant, neonatal and early death was U-shaped with the nadir at 39 weeks. There was a statistically significant increase in early death at 37 compared to 40 weeks' gestation [OR (95 %) CI = 1.929(1.172-3.176)]. No statistical increase was found in any of the other mortality risks.

There is an increased risk in early death with ERCD performed at 37 weeks. Our study provides evidence of neonatal harm beyond the reported morbidity risks.