Neonatal outcome by planned mode of delivery in women with a body mass index of 35 or more: a retrospective cohort study

Objective To compare neonatal outcomes of women with a body mass index (BMI) of ≥35 kg/m 2 who underwent a trial of labour with those of women who underwent a planned primary caesarean section (CS). Design A retrospective cohort study of births between April 2012 and March 2014. Setting A provincial database: Better Outcomes Registry & Network (BORN) Ontario, Canada. Population A cohort of 8752 women with a BMI of ≥35 kg/m 2 who had a singleton birth at 38–42 weeks of gestation. Methods Neonatal outcomes were compared between women who underwent a trial of labour (with either a successful vaginal birth or intrapartum CS) and those who underwent a planned CS. Main outcome measure A composite of any of the following outcomes: intrapartum neonatal death, neonatal intensive care unit admission, 5‐minute Apgar score of <7 or umbilical artery pH of <7.1. Results During the study period, 8433 (96.4%) women had a trial of labour and 319 (3.6%) had a planned CS. Intrapartum CS was performed in 1644 (19.5%) cases. There was no association between planned mode of delivery and the primary outcome (aOR 0.80, 95% CI 0.59–1.07). The primary outcome was lower among women who had a successful trial of labour (aOR 0.67, 95% CI 0.50–0.91) and was higher among women who had a failed trial of labour (aOR 1.74, 95% CI 1.21–2.48), compared with women who underwent a planned CS. Conclusions In women with a BMI of ≥35 kg/m 2 at a gestational age of 38–42 weeks, neonatal outcomes are comparable between planned vaginal delivery and planned CS, although a failed trial of labour is at risk of adverse neonatal outcome. Tweetable abstract Neonatal outcomes are not affected by planned mode of delivery in women who are obese, with a BMI of ≥35 kg/m 2 .