The Association Between Maternal Body Mass Index and Spontaneous Preterm Birth Among Patients Prescribed Vaginal Progesterone for Short Cervix [ID 2683530

Abstract

INTRODUCTION: Vaginal progesterone decreases the risk of spontaneous preterm birth (sPTB) and adverse neonatal outcomes in patients with short cervix (cervical length [CL] <2.5 cm) between 16 and 24 weeks. Few studies have assessed the efficacy of this intervention in patients with obesity. We evaluate the association between maternal body mass index (BMI) and sPTB among patients prescribed vaginal progesterone for short cervix. METHODS: This was an IRB-approved retrospective cohort study of patients prescribed vaginal progesterone for short cervix at Mount Sinai Hospital. Exclusion criteria included prior PTB, cerclage, or progesterone treatment in prior pregnancy, and multifetal gestation. Logistic regression models assessed the association between BMI categories (BMI less than 25, BMI 25.0–29.9, BMI 30 or higher) and PTB less than 37 weeks, PTB less than 34 weeks, and neonatal intensive care unit (NICU) admission adjusting for nulliparity, CL at diagnosis, and insurance status. RESULTS: Of the 210 patients included, 86 had BMI of less than 25 (41%), 72 had BMI of 25.0–25.9 (34.4%), and 52 had BMI of 30 or higher (24.8%), and 79 experienced sPTB (37.6%). Although BMI was not associated with sPTB less than 37 weeks, the odds of sPTB at less than 34 weeks among individuals with BMI of 30 or higher was 3.03 times the odds for those with BMI of less than 25 (95% CI, 1.13–8.14). The odds of NICU admission among those with BMI of 30 or higher is 2.82 times the odds among those with BMI of less than 25 (95% CI, 1.23, 6.46). CONCLUSION: This study demonstrates obesity is associated with sPTB at less than 34 weeks and NICU admission among those prescribed vaginal progesterone for short cervix. Larger studies are needed to evaluate the effect of BMI on efficacy of vaginal progesterone.