(436) Association of BMI on surgical and pregnancy outcomes in patients undergoing non-emergent vaginal cerclage

Objective: Patients with obesity (BMI ≥ 30 kg/m2) have more surgical and pregnancy complications than those without. We studied the association of BMI on surgical risks and perinatal outcomes in patients undergoing non-emergent vaginal cerclage.

Study Design: Retrospective cohort study of patients with non-anomalous singleton gestations who had a non-emergent history (Hx)- or ultrasound (US)-indicated vaginal cerclage at a single tertiary center 1/2013-4/2021. Patients were defined as obese or non-obese (BMI < 30). Our primary outcome was birth gestational age (GA). Secondary outcomes included preterm birth (PTB), operative morbidity, and selected perinatal outcomes. Baseline characteristics, primary, and secondary outcomes were compared in bivariate analysis. Linear regression modeled the relationship between BMI and birth GA; possible confounders were considered in these models.

Results: Of 258 non-emergent vaginal cerclages analyzed, 110 (43%) were non-obese (BMI 25 ± 3.3) and 148 (57%) obese (BMI 38 ± 6.7). There were 175 Hx- and 83 US-indicated procedures. The obese group tended to be Non-Hispanic Black (n=148) and had more prior pregnancy losses (p=0.003). The obese group delivered at significantly earlier mean GAs, with greater rates of PTB across all viable GA ranges, had earlier GA at membrane rupture, and shorter cerclage durations (Table). For every BMI unit increase, there was a decrease of 0.14 weeks in birth GA (β= -0.14 wk/BMI unit, p=0.004). Obese patients also had significantly higher estimated blood loss and longer operative times, but similar operative morbidity, lengths of stay, and readmissions. Obesity was associated with different birth indications, as well as higher neonatal composite morbidity (Table). After controlling for race, cerclage indication, and obstetric history, there was still a significant effect of BMI on birth GA (β= -0.10, p=0.038).

Conclusion: Following non-emergent cerclage, patients with obesity delivered earlier than those without. The inverse effect of BMI on birth GA persisted after controlling for selected confounders.