Factors Associated with Failed Trial of Labor after Cesarean, among Women with Twin Gestation-A Multicenter Retrospective Cohort Study.

Objective: Twin trial of labor after a cesarean section (TOLAC) is associated with a lower success rate of vaginal delivery than singleton TOLAC, and a higher rate of adverse outcomes in comparison to an elective repeat cesarean delivery. This study aims to investigate the factors associated with failed TOLAC, among women with twin gestation. Study design: A multicenter retrospective cohort study was undertaken. All women with twin pregnancies attempting a trial of labor after a previous cesarean in two university-affiliated obstetrical centers, between 2005 and 2021 were included. The study population included women with a twin gestation where twin A presented in the vertex position, a single previous low segment transverse section, and those who were eligible for a vaginal delivery. Labor, maternal, and neonatal characteristics were compared. A univariate analysis was undertaken, followed by multivariate analysis (aORs; [95% CI]). Results: A total of 160 women attempting a twin TOLAC were included. Vaginal birth after cesarean was achieved in 86.3% of these cases. Assisted reproductive technology (ART), the lack of oxytocin use for augmentation during labor, the lack of epidural analgesia, and preterm birth before 34, 32, and 28 gestational weeks were all found to be associated with failed TOLAC. In the multivariate analysis, cervical dilation on admission (aOR 0.6 [0.40−0.82], p < 0.01), no use of oxytocin (aOR 5.2 [1.36−19.73], p = 0.02), gestational age at delivery (aOR 0.8 [0.65−1.00], p = 0.047) and lack of epidural analgesia (aOR 4.5 [1.01−20.16], p = 0.049), were all found to be significantly associated with failed TOLAC. Conclusion: In the investigated population of women with twins undergoing TOLAC, the use of epidural analgesia, the use of oxytocin and increased cervical dilation to the delivery room are associated with a higher rate of vaginal delivery, and may reduce the risk of repeat cesarean delivery.