Document Type


Degree Name



Dept. of Public Health & Preventive Medicine.


Oregon Health & Science University


Introduction: Maternal obesity is common in pregnancy and increases the risk of several adverse perinatal outcomes. Many such outcomes are also related to gestational age at delivery, making the timing of delivery in obese women of particular concern. The objective of this study is to investigate the relationship between term elective induction of labor (eIOL) and perinatal outcomes in obese women and determine the optimal timing and cost-effectiveness of eIOL in the setting of maternal obesity. Methods: We performed a retrospective cohort study comparing eIOL versus expectant management in deliveries among obese women in California in 2007. Comparisons were made for 37, 38, 39, and 40 weeks of gestation. Our primary outcome was cesarean delivery, and several additional maternal and neonatal morbidities were examined. We also built a cost-effectiveness model comparing outcomes and costs following eIOL at 37-41 weeks in a theoretic cohort of 800,000 obese women. Results: The odds of cesarean delivery were lower among nulliparous women with eIOL at 37 weeks and 39 weeks compared to expectant management. Among multiparous women with a prior vaginal delivery, eIOL at 37, 38, and 39 weeks was associated with lower odds of cesarean. Additionally, eIOL at 38, 39, and 40 weeks was associated with lower odds of macrosomia, and there were no differences in the odds of operative vaginal delivery, lacerations, brachial plexus injury, or respiratory distress syndrome. Decision analysis revealed that eIOL at 38 weeks would maximize total quality-adjusted life years. Delivery at 38 weeks was an incrementally cost-effective strategy compared to expectant management until a later gestational age in the majority of scenarios. Conclusion: In obese women, eIOL is not associated with an increased risk of cesarean delivery or adverse perinatal outcomes when compared with expectant management. Balancing the gestational age-related risks of stillbirth and neonatal morbidities, the optimal timing of delivery is at 38 weeks in obese women, and eIOL at 38 weeks is a cost-effective strategy.




School of Medicine



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