Risk of complications in the late vs early days of the 42nd week of pregnancy: A nationwide cohort study.

Abstract

Uncertainty remains about the most appropriate timing of induction of labor in late-term pregnancies. To address this issue, this study aimed to compare the risk of neonatal morbidity and pregnancy- and birth-related complications between gestational age (GA) 41+4 -42+0 and GA 41+0 -41+3 weeks. This nationwide registry-based cohort study included singleton births without major congenital malformations, with registered GA, and with intended vaginal delivery at GA 41+0 - 42+0 weeks between 2009 and 2018 in Denmark. Logistic regression models were used to estimate the crude risk ratio and adjusted risk ratio (RRA ) of neonatal and obstetric adverse outcomes in births at GA 41+4 - 42+0 weeks compared with GA 41+0 - 41+3 weeks. The results were adjusted for relevant confounders, including induction of labor. A higher incidence of neonatal morbidity and birth complications was observed in births at GA 41+4 -42+0 weeks than in births at GA 41+0 -41+3 weeks. Neonatal morbidities included an increased risk of low Apgar score (Apgar 0-6 after 5min; RRA 1.17, 95% confidence interval [CI] 1.01-1.34), meconium aspiration (RRA 1.25, 95% CI 1.06-1.48), need for respiratory support (continuous positive airway pressure; RRA 1.09, 95% CI 1.03-1.15), and a composite outcome of need for comprehensive treatment at a neonatal department or neonatal death (RRA 1.65, 95% CI 1.29-2.11). Birth complications included emergency cesarean section (RRA 1.17, 95% CI 1.14-1.21), severe lacerations (RRA 1.11, 95% Cl 1.04-1.17), and increased blood loss after birth (RRA 1.13, 95% CI 1.06-1.21). Births at GA 41+4 -42+0 weeks were associated with an increased risk of neonatal morbidity and birth complications compared with births at GA 41+0 -41+3 weeks. The results of this study may aid clinicians in deciding when to recommend induction of labor in late-term pregnancies.