Trial of labor following cesarean in preterm deliveries: success rates and maternal & neonatal outcomes- a multicenter retrospective study

Abstract Purpose: To evaluate rates of vaginal birth after cesarean (VBAC) among parturients attempting preterm trial of labor following a cesarean delivery (TOLAC) vs. term TOLAC.Methods: A multicenter historic cohort study at two university-affiliated centers between August 2005 and March 2021. Parturients in their 2nd delivery, attempting TOLAC after a single low segment transverse cesarean delivery (CD) were included. We retrospectively examined computerized medical records of all preterm (<37 weeks) and term (37-42 weeks) births. Multifetal gestations and post-term deliveries (≥42 weeks) were excluded. A univariate analysis was conducted followed by a multivariate analysis. Results: 4,865 second deliveries following previous CD were identified; 212 (4.4%) preterm and 4653 (95.6%) term. Hypertensive disorders, diabetes and fertility treatments were significantly more prevalent in the preterm group. VBAC rate was significantly lower in preterm group (57.5% vs 79.7%., p<0.01), including both spontaneous and vaginal-assisted deliveries. In multivariate analysis, preterm TOLAC was independently associated with TOLAC failure [adjusted odds ratio (aOR) 2.24, [95% confidence interval (CI) 1.62-3.09]. Overall, maternal outcomes were favorable. Rates of uterine rupture, re-laparotomy and post-partum hemorrhage were comparable between groups. Neonatal outcomes were less favorable among the preterm group, however, preterm vs. term TOLAC was not associated with low 5-minute Apgar score (aOR 1.76, 95% CI 0.92-3.40).Conclusion: In our study, VBAC rates were lower in preterm compared to term deliveries. Maternal outcomes were comparable. Neonatal outcomes were less favorable in the preterm group, more likely due to prematurity than delivery mode.