Rate of cesarean delivery among patients with class III obesity at term based on body mass index: A retrospective cohort study

OBJECTIVES: This study investigates the risk of cesarean delivery based on body mass index (BMI) in patients with class III obesity who undergo induction of labor. METHOD: This was a retrospective cohort study set in a university hospital. Study participants included patients presenting for delivery at term with class III obesity at the time of admission. A retrospective chart review was conducted of patients with a pre-delivery BMI ≥40 who delivered between May 2016 and December 2020 at a single institution. Patients were divided into the following BMI groups: 40-44.9, 45-49.99, 50-59.99, ≥60. Demographic and other clinical features were analyzed using analysis of variance and Fisher tests across BMI groups. Rates of labor induction and cesarean delivery (CD) were further analyzed by logistic regression. RESULTS: We identified 1010 patients with pre-pregnancy BMI ≥40 who delivered in the study period, of whom 497 met the study criteria. The median BMI in this population was 43.9 (interquartile range: 41.8-48.5, range 40.0-92.9). Twenty-seven percent of patients who underwent an induction of labor (IOL) delivered via CD compared to 12% for patients who presented in spontaneous labor. There were higher rates of induction seen in patients as BMI increased, but this effect was not seen in patients with BMI 60 or higher. The rate of CD was increased in patients who underwent IOL (P = 0.0332). This finding was only seen for those undergoing an elective IOL (P = 0.0088) but not a medically indicated IOL (P = 0.3588). CONCLUSION: Rates of induction of labor are higher in patients with higher BMI. In our cohort, those who underwent elective IOL were more likely to deliver via CD. Further study is needed to evaluate outcomes for patients with a BMI of 60 and greater, and more clarity is needed around recommendations for timing of elective induction of labor in patients with class III obesity.