(203) Induction of Labor After Cesarean: Factors Associated with Repeat Cesarean Delivery

Prior vaginal delivery (VD), more favorable Bishop score, and non-recurring indication for primary Cesarean Delivery (pCD), e.g. fetal malpresentation are associated with successful Vaginal Birth After Cesarean (VBAC). However this research is in patients in spontaneous labor. Less is known about factors influencing successful Trial of Labor after Cesarean (TOLAC) among patients undergoing an induction of labor (IOL). Therefore, we aimed to evaluate risk factors for failed IOL after Cesarean (IOLAC).  

Study Design:
This retrospective cohort study included patients at 2 hospitals who underwent IOLAC in 2024. Term patients with a history of 1 pCD were included. The primary outcome was failed IOLAC (defined as repeat CD, rCD). Association between mode of delivery and patient characteristics were calculated using Fisher’s Exact, Student’s t-, Chi-Square, and Wilcoxon Rank Sum tests where appropriate. Multivariable stepwise regression analyses with statistically significant associations with mode of delivery were utilized to predict rCD.

Results:
Out of the 14,205 patients who delivered in 2024, 485 were TOLACs, 232 (50.7%) underwent IOL, and 201 were term. 133 patients (66.2%) had a VBAC, and 68 (33.8%) had an rCD. Table 1 compares characteristics between those who had a VBAC vs. rCD. In univariate analysis, patients with a prior VD before their CD, prior VBAC, and higher Bishop were less likely to have an rCD. Indication for pCD and IOL method were also found to be significantly associated with mode of delivery. In multivariable regression modeling, only higher Bishop, history of prior VBAC, and indication for pCD remained in the final regression model. Among the indications for pCD, a prior history of failed induction had the highest risk of rCD (RR: 4.68, CI: 1.54-14.29) when controlling for prior VBAC and Bishop.

Conclusion:
In this diverse cohort of 201 IOLAC patients, more than 65% were successful. Having a lower Bishop, no prior VBAC, and having a pCS for failed induction are factors predictive of risk of rCD. Future research regarding specific methods of IOLAC and associated outcomes is warranted.