Evaluating the Impact of a Trial of Labor After Cesarean Section on Labor Duration: A Retrospective Cohort Study

Abstract Introduction: Repeat cesarean section (C-section) is associated with an increased risk of maternal complications and a reduction in quality of life (QOL). Trial of Labor After C-section (TOLAC) may reduce the recurrence of cesarean deliveries. Uterine rupture, a complication of TOLAC, is a serious obstetric complication, with prolonged labor duration suggested as a risk factor. However, there are no reports examining labor duration in women with cesarean scars, considering the termination of labor through cesarean section and selection bias. Our study aimed to investigate the impact of cesarean scars on the labor duration of TOLAC patients, considering these factors. Methods: From January 1, 2012, to December 31, 2021, we investigated a cohort of 2,964 individuals who attempted vaginal delivery at a single medical center, categorizing them into TOLAC and non-TOLAC groups. Propensity scores were generated based on factors that could influence labor duration, and survival analysis was conducted after applying Inverse Probability of Treatment Weighting (IPTW). We evaluated the robustness of the results by propensity score matching and bootstrapping as a sensitivity analysis. Results: Results from Cox proportional hazards regression analysis indicated that the unadjusted hazard ratio was 0.83 (95% Confidence Interval (CI): 0.70-0.98, p=0.027), whereas the IPTW-adjusted hazard ratio was 0.98 (95% CI: 0.74-1.30, p=0.91). Conclusion: Factors such as maternal physique and fetal characteristics influence labor duration, with the impact of cesarean scars being limited. Our findings were consistent with previous studies and provided supportive evidence.