Optimal Plan for Delivery in Women with Obesity: A Large Population-based Retrospective Cohort Study Using the Better Outcomes Registry and Network (BORN) Database

Objective: To discern the optimal plan for delivery in nulliparous women with obesity at term gestation. Design: Large population-based retrospective cohort study Setting: Maternity hospitals in Ontario, Canada Population: Nulliparous women with obesity (BMI>30) with live, singleton, uncomplicated term gestations (37+0 to 41+6 weeks) between April 1st, 2012 and March 31st, 2019 Methods: Women were divided by plan for delivery (expectant management, induction of labour and no-labour caesarean section). The outcomes of interest were adverse delivery outcomes. Analyses were conducted using multivariable regression models. Analyses were stratified by each week of gestational age and by obesity class. Main Outcome Measures: The primary outcome was the Adverse Outcome Index (AOI), a binary composite of 10 maternal and neonatal adverse events. The Weighted Adverse Outcome Score (WAOS) was the secondary outcome. It provides a weighted score of each adverse event included in the AOI. Results: No-labour caesarean section reduced the risk of adverse delivery outcome by 41% (aRR 0.59, 95%CI [0.50, 0.70]) compared to expectant management at term gestation. There was no statistically significant difference in adverse birth outcomes when comparing induction of labour to expectant management (aRR 1.03, 95% CI [0.96, 1.10]). The greatest benefit to no-labour caesarean section was observed in the reduction of adverse neonatal events (aRR 0.70, 95% CI [0.57, 0.87]) particularly at 39 weeks of gestation. Conclusion: In women with obesity, no-labour caesarean section reduces adverse birth outcomes. Funding: Canadian Institute for Health Research (CIHR) (#MFM146444). Keywords: Plan for delivery, Induction of Labour, Caesarean Section, Obesity