(130) Vaginal birth after cesarean (VBAC) success and uterine rupture among twin compared to singleton gestation

Objective: Rates of vaginal birth after cesarean (VBAC) success and uterine rupture risk are well described for singleton gestations undertaking a trial of labor after cesarean (TOLAC). However, data are limited for twin gestations. We aimed to evaluate rates of VBAC success and uterine rupture among twin compared to singleton gestations undergoing TOLAC.

Study Design: Retrospective cohort study including deliveries >20 weeks’ gestation from 2016-2018 with data available in the MarketScan Research Database. Individuals with prior cesarean delivery and undertaking TOLAC were included. Those with contraindication to vaginal delivery or higher order multiples were excluded. The primary outcome was successful VBAC, defined as vaginal delivery among those with history of cesarean. The secondary outcome was uterine rupture. Outcomes and covariates were identified using ICD-10 codes. Univariate analyses compared baseline characteristics for twins compared to singleton gestations. Multivariate logistic modeling estimated the association between twin compared to singleton TOLAC and the outcomes.

Results: Of 51,214 eligible deliveries, 10,368 (20.2%) were twin gestations. Twin compared to singleton gestations were more likely to have chronic hypertension (10.3% vs 8.1%, p< 0.001) and gestational diabetes (14.6% vs 12.5%, p< 0.001). In unadjusted and adjusted modeling, twin compared to singleton TOLAC was associated with lower VBAC success (14.40% vs 18.18%; OR 0.76, 95% CI 0.71-0.80; aOR 0.78, 95% CI 0.74-0.83) but no statistically significant difference in uterine rupture (0.65% vs 0.84%; OR 0.77, 95% CI 0.59-1.0; aOR 0.77, 95% CI 0.56-1.01; Figure).

Conclusion: TOLAC in twin gestations compared to singletons was associated with decreased VBAC success but no difference in rates of uterine rupture. This information may be used to help counsel patients with twin gestations considering TOLAC.