Abstract
Background
With increasing rates of labor induction and trial of labor after cesarean, induction of labor after cesarean (IOLAC) is becoming more common. However, predictors of success among patients undergoing IOLAC, particularly those with an unfavorable cervix, remain unclear.
Objective
To identify risk factors associated with failed IOLAC in patients with unfavorable Bishop scores.
Study Design
This retrospective cohort study of patients at two academic hospitals who underwent IOLAC in 2024 included full-term patients with one prior cesarean delivery and an unfavorable Bishop score (<8) at the time of induction. The primary outcome was failed IOLAC, defined as repeat cesarean delivery (rCD). Associations between delivery mode and clinical characteristics were evaluated using univariate analyses and multivariable stepwise regression.
Results
The cohort included 201 patients, with an overall vaginal birth after cesarean (VBAC) rate of 66.2%. Successful IOLAC was more likely among patients with a prior vaginal delivery before cesarean (p=0.015) or prior VBAC (p<0.001), and among those with higher Bishop scores (p<0.001). Prior cesarean for failed induction and arrested labor were associated with a 56% (RR 1.56, 95% CI 1.01–2.39) and 90% (RR 1.90, 95% CI 1.24–2.91) increased risk of rCD, respectively. (RR 1.56, 95% CI 1.01–2.39). Cesarean for malpresentation was associated with lower rCD risk (RR 0.51, 95% CI 0.27–0.89).
Conclusion
Prior VBAC and higher Bishop score predict IOLAC success, while prior cesarean for labor arrest or failed induction increases rCD risk in those with unfavorable cervices. These findings may guide counseling and future research.