Maternal body mass index, maneuvers, and neonatal morbidity associated with shoulder dystocia

Abstract

To compare the frequency and type of maneuvers used to resolve social dystocia (SD) by maternal pre-pregnancy body mass index (BMI) and the association between BMI and neonatal adverse outcomes following SD. We conducted a retrospective cohort study of pregnant individuals who experienced an SD at delivery from June 2012-July 2021 at a tertiary care center. We included singleton nonanomalous livebirths ≥36 weeks’ gestation. The primary exposure was pre-pregnancy BMI categorized as: < 30 kg/m2, 30-34.9- kg/m2, and ≥35 kg/m2. The composite neonatal outcome included neonatal injury, seizures, hypoxic ischemic encephalopathy, 5-minute APGAR < 7, and secondarily, NICU admission and neonatal acidemia (pH < 7.10). SD duration and number and types of maneuvers were compared by BMI groups. Multivariable logistic regression was used and adjusted for diabetes in pregnancy, operative vaginal delivery, and nulliparity. Among 883 individuals who experienced an SD at delivery, 608 (68.9%) had a BMI < 30, 161 (18.2%) were BMI 30-34.9, and 114 (12.9%) were BMI ≥35. The median duration of SD was 40 (IQR 30, 60) seconds and did not vary by maternal BMI. Deliveries complicated by BMI ≥35 were more likely to require ≥3 maneuvers compared to those with non-obese BMI (aOR 2.06, 95% CI 1.33-3.19). Suprapubic pressure (90.0%) and delivery of the posterior arm (40.9%) were the most commonly used maneuvers in all groups. Rubin’s and delivery of the posterior arm maneuvers were more commonly used in the BMI ≥35 group compared to BMI < 30 (RR 1.49, 95% CI 1.11-2.01; RR 1.32, 95% CI 1.08-1.61, respectively) categories. Composite neonatal adverse outcomes did not differ by BMI, but neonatal injury was more common in those with BMI ≥35 (aOR 2.03, 95% CI 1.11-3.75). Interaction between BMI category and number of maneuvers was not significant (p=0.09). Among pregnant individuals who experienced a SD, increased pre-pregnancy BMI was associated with increased number of maneuvers performed during a SD, but not its duration. Risk of neonatal injury following SD is higher if maternal BMI is ≥35 kg/m2.View Large Image Figure ViewerDownload Hi-res image Download (PPT)