Prediction of successful preterm vaginal birth after cesarean among women who never delivered vaginally

Purpose: We aimed to determine the factors associated with a successful trial of labor after cesarean (TOLAC) in the setting of preterm delivery of women with no prior vaginal delivery. Methods: A retrospective cohort study conducted at two tertiary medical centers during 2010–2020, including all TOLACs with a single cesarean delivery and no prior vaginal delivery, delivering a singleton preterm newborn. Factors associated with successful vaginal delivery were examined by multivariable analysis. Results: Of the 232 women with TOLAC who constituted the study cohort, 178 (76.7%) successfully delivered vaginally. Previous cesarean delivery characteristics did not differ between study groups. Maternal characteristics did not differ between TOLAC success and failure groups. The median gestational age at delivery was 35 ^3/7 weeks (IQR 34 ^0/7–36 ^0/7). The rate of epidural analgesia administration was higher in the TOLAC success group (54.5% vs. 35%, p = 0.013). Preterm premature rupture of membranes (PPROM) rate was lower in the TOLAC success group (53.9% vs. 83%, p < 0.001). The rate of induction of labor did not differ between TOLAC success and TOLAC failure groups. There were no cases of uterine rupture. In a multivariable logistic regression analysis, PPROM was the only independent factor associated with TOLAC success [adjusted OR (95% CI) 0.29 (0.10–0.83), p = 0.030]. Conclusion: TOLAC in preterm deliveries among women with no prior vaginal delivery is safe, has a high success rate and PPROM is the only negatively associated predictor.