Influencing factors for trial of labor after cesarean section in women becoming pregnant again

Abstract:

Objective To investigate the influencing factors for the success rate of vaginal birth after cesarean section（VBAC），to guide clinical decision-making for trial of labor after cesarean section（TOLAC），and to improve the success rate of VBAC and reduce the occurrence of adverse maternal and fetal outcomes.Methods A retrospective analysis was performed for 452 pregnant women who experienced TOLAC in Obstetrics Center of Women and Children’s Hospital of Chongqing Medical University（Chongqing Health Center for Women and Children） from January 2020 to October 2022，among whom 342 experienced VBAC and 110 experienced failed TOLAC. According to the final mode of delivery，110 pregnant women were selected as VBAC group，and 110 were selected as failed TOLAC group. Univariate analysis and multivariate logistic regression analysis were used to investigate the influencing factors for VBAC，and pregnancy outcome was compared between the two groups.Results In this study，the overall VBAC rate was 75.67%（342/452），and the TOLAC failure rate was 24.33%（110/452）. The univariate analysis of prenatal factors showed that there were significant differences between the VBAC group and the failed TOLAC group in gestational age（38.44±2.13 weeks vs. 38.96±1.34 weeks，P<0.05） and the proportion of pregnant women with induction of labor due to the history of abnormal pregnancy（11.82% vs. 2.80%，P<0.05） or pregnancy comorbidities（32.73% vs. 20.56%，P<0.05），and there were also significant differences between the two groups in cervical Bishop score on admission（5.15±1.69 vs. 3.71±1.52，P<0.001），the proportion of women with a history of vaginal delivery（32.73% vs. 20.56%，P<0.001），and the proportion of women with spontaneous delivery（86.36% vs. 17.76%，P<0.001）. The univariate analysis of maternal and infant pregnancy outcomes showed that compared with the failed TOLAC group，the VBAC group had a significantly lower body weight of neonates（3 191.82±489.00 g vs. 3 334.15±375.99 g，P<0.05） and significantly lower blood loss within 24 hours after delivery（408.75±142.31 mL vs. 560.85±168.61 mL，P<0.05）.］There were 7 patients with incomplete uterine rupture in the failed TOLAC group. There were no significant differences between the two groups in blood transfusion，puerperal infection，and 5-minute Apgar score of neonates. There was no death of pregnant and parturient women or perinatal infants. The multivariate logistic regression analysis showed that cervical Bishop score on admission（odds ratio ［OR］=0.122，95%CI： 0.010-1.441），history of vaginal delivery（OR=0.034，95%CI： 1.297-715.194），premature delivery（OR=186.54，95%CI： 2.225-15638.578），and spontaneous labor（OR=52.37，95%CI： 8.949-306.517） were influencing factors for VBAC.Conclusion Gestational weeks，history of vaginal delivery，history of induction of labor due to abnormal pregnancy，pregnancy comorbidities，cervical Bishop score on admission，spontaneous labor，and history of premature delivery are influencing factors for VBAC. The VBAC group has lower blood loss within 24 hours after delivery than the failed TOLAC group.