Trial of labor after previous single cesarean delivery in grand-multiparous women: a retrospective cohort study

Purpose: To compare pregnancy outcomes in grand-multiparous (GMP) women with and without one previous cesarean delivery (CD), and to evaluate the number of previous successful vaginal deliveries after a CD needed to reduce the complication rate of trials of labor after a previous CD. Methods: This is a retrospective cohort study of women with singleton pregnancy at term who had a trial of vaginal delivery between 2007 and 2014 at a tertiary medical center. We compared pregnancy outcomes in GMP women with and without one previous cesarean delivery. The primary outcome was mode of delivery and secondary outcomes were uterine rupture and composite maternal and neonatal morbidity. For the secondary objective, we compared pregnancy outcomes in women in TOLAC, stratified by the number of previous vaginal deliveries. Results: Overall, 2815 GMP women met the study criteria, of which 310 (11%) had a previous cesarean delivery. The rate of a successful vaginal deliveries (VBAC) was similar, regardless of the presence of a previous cesarean delivery. No other differences in outcomes were found between the groups. In a secondary analysis, it was found that the presence of a single previous VBAC (compared to no previous VBACs) increased the odds of achieving a vaginal delivery in the next trial of labor after cesarean delivery (TOLAC) (aOR 5.66; 95% CI 3.73–8.60), and decreased the risk of maternal or neonatal adverse outcomes (aOR 0.62; 95% CI 0.39–0.97, and aOR 0.49; 95% CI 0.25–0.97, respectively). Multiple prior VBACs (as compared to a single prior VBAC) did not increase the odds of achieving another VBAC. Conclusion: Grand-multiparous women with and without previous uterine scar have comparable pregnancy outcomes. Additionally, after the first VBAC, additional successful VBACs do not improve the success rate in the next TOLAC.