The Feasibility of a Trial of Labor after Two Cesarean Deliveries: Outcomes and Prognostic Factors for Success

Objective This study aimed to determine whether a trial of labor after two cesarean deliveries (TOLAC2) increases the risk of adverse maternal and neonatal outcomes and identify prognostic factors for TOLAC2 success. Study Design A retrospective cohort study was conducted at a single medical center. The study group was comprised of women with a history of TOLAC2. Outcomes were compared with women undergoing trial of labor after one previous cesarean delivery (TOLAC1). The primary outcome was trial of labor after cesarean delivery (TOLAC) success. Secondary outcomes included mode of delivery, uterine rupture, and combined adverse outcome (CAO; uterine rupture, postpartum hemorrhage, 5-minute Apgar score < 7, pH < 7.1). Logistic regression was used for the multivariate analysis to identify prognostic factors for TOLAC2 success. Results A total of 381 women who underwent TOLAC2 were compared with 3,635 women who underwent TOLAC1. Women attempting TOLAC2 were less likely to achieve vaginal births after cesarean delivery (VBAC; 80.8 and 92.5%; odds ratio [OR]: 0.35; 95% confidence interval [CI]: 0.26-0.47; p < 0.001) and more likely to experience uterine rupture (0.8 vs. 0.2%; OR: 4.1; 95% CI: 1.1-15.9; p = 0.02) but not CAO (4.2 vs. 4.8%; OR: 0.88; 95% CI: 0.5-1.5; p = 0.3). TOLAC2 women with no previous vaginal deliveries had a lower chance of VBAC and a higher risk of uterine rupture compared with TOLAC1 women without a prior vaginal delivery (45.2 vs. 86.3%; OR: 0.13; 95% CI: 0.07-0.25; p < 0.001; 2.3 vs. 0%) and TOLAC2 women with a prior vaginal delivery (45.2 vs. 85.3%; OR: 0.14; 95% CI: 0.1-0.3; p < 0.0001; 2.4 vs. 0.6%; OR: 4.1; 95% CI: 0.4-46.3; p = 0.3). Multivariate analysis revealed that a history of vaginal delivery is an independent predictor of TOLAC2 success. Conclusion Women attempting TOLAC2 are less likely to achieve VBAC and are at greater risk of uterine rupture compared with those attempting TOLAC1. Despite these risks, the overall success rates remain very high, and the absolute risk of adverse outcomes is still very low. Prior vaginal delivery seems to have a protective effect on TOLAC outcomes. These data should be used to counsel women and assist in decision-making when considering the mode of delivery in women with two previous cesarean sections. Key Points TOLAC2 has a lower chance of success and higher rate of uterine rupture compared with TOLAC1. Previous vaginal delivery is an independent predictor of TOLAC2 success. Overall TOLAC2 outcomes are associated with high chances of success and low risk of uterine rupture.