For Patients Undergoing an Induction of Labor, Does Increased Body Mass Index Necessitate Higher Doses of Misoprostol? [ID 2683640

Abstract

INTRODUCTION: Obesity is associated with prolonged induction of labor (IOL). This study aimed to investigate the association between body mass index (BMI) and number of misoprostol administrations in patients undergoing IOL. METHODS: This was a retrospective cohort analysis of patients undergoing IOL at a single institution from June 2012 to January 2023. Singleton, term patients receiving at least one dose of misoprostol were included (n=4,780). Body mass index at admission was defined as normal (18.5 to <25.0), overweight (25 to <30), Class I obesity (30 to <35), Class II obesity (35 to <40), and Class III (≥40). The primary outcome was the number of misoprostol doses. Demographics were compared by BMI category using chi-square and ANOVA. Crude and multiple linear regression was used to generate parameter estimates and 95% CIs. RESULTS: Among the cohort, 4.6%, 23.9%, 31.3%, 21.0%, and 19.2% were normal, overweight, Class I, Class II, and Class III, respectively. Public insurance, cHTN, HDP, and pre-gestational diabetes were positively associated with increasing BMI (P<.0001). Mean misoprostol doses significantly increased across BMI categories (from normal 3.3 [SD 2.4] to Class III 5.0 [SD 3.6]; P<.0001). Compared to normal BMI, model estimates increased for overweight, 0.75 (CI, 0.29–1.22); Class I, 1.03 (CI, 0.57–1.48); Class II, 1.40 (CI, 1.93–1.87); and Class III, 1.75 (CI, 1.28–2.22). After adjustment for aforementioned demographics, these estimates were attenuated but still significant. CONCLUSION: Increasing BMI is associated with increased average dose of misoprostol during IOL. This highlights the need to investigate safety of increased misoprostol dosing for IOL among obese patients.