Duration of a vaginal birth after cesarean section depending on the degree of cervical dilation in the prior cesarean delivery: A retrospective study

OBJECTIVE: Labor and birth lead to significant immunological and regenerative changes in the uterus, such that multiparous women typically experience faster and more effective labor than primiparous women. In this retrospective study, we examined the influence of labor activity and childbirth progress in the previous pregnancy on the duration of vaginal delivery of a second child in women with a history of one cesarean section. METHODS: A total of 200 women bearing their second child with a trial of labor after cesarean who presented for delivery between January 2018 and December 2022 at the Clinic St. Hedwig (a tertiary maternity hospital of University of Regensburg, Germany) were included. Three subgroups were analyzed: women with a history of elective cesarean section, those with a history of cesarean section during the first stage of labor, and those with a history of cesarean section during the second stage of labor. The two stages were defined depending on the cervical dilation (first stage <10 cm, second stage: full dilatation). The duration of labor was defined as time between regular contractions or time of rupture of the membranes (whatever was first) to childbirth. A t-test and Pearson correlation analysis were conducted (using SigmaPlot 14.0). RESULTS: In 75.5% of cases (151/200), a vaginal birth (VBAC, vaginal birth after cesarean section) was achieved, and in 24.5% of cases (49/200), an unplanned repeat cesarean section was performed. The median duration of labor for VBAC in women with a history of elective cesarean was 12.2 h (interquartile range [IQR] 6.9-19.5), for those with a history of cesarean during the first stage of labor 10.0 h (IQR 6.0-16.2), and for those with a history of cesarean during the second stage of labor 8.0 h (IQR 3.9-12.0). CONCLUSION: Women with a history of cesarean during the second stage of labor deliver 4 h faster than women with a history of elective cesarean. Even if labor must be terminated during the first stage, an advanced degree of cervical dilation has a shortening effect on the duration of a subsequent VBAC.