Factors associated with failed induction of labor after cesarean delivery with an unfavorable cervix at term.

BACKGROUND

With increasing rates of induction of labor and trial of labor after cesarean, induction of labor after cesarean is becoming more common. However, the predictors of success among patients undergoing induction of labor after cesarean, particularly those with an unfavorable cervix, remain unclear.

OBJECTIVE

This study aimed to identify risk factors associated with failed induction of labor after cesarean in patients with unfavorable Bishop scores.

STUDY

DESIGN

This retrospective cohort study of patients at 2 academic hospitals who underwent induction of labor after cesarean in 2024 included full-term patients with 1 previous cesarean delivery and an unfavorable Bishop score (<8) at the time of induction of labor. The primary outcome was failed induction of labor after cesarean, defined as repeat cesarean delivery. Associations between delivery mode and clinical characteristics were evaluated using univariate analyses and multivariate stepwise regression analyses.

RESULTS

The cohort included 201 patients, with an overall vaginal birth after cesarean rate of 66.2%. Successful induction of labor after cesarean was more likely among patients with a previous vaginal delivery before cesarean (P=.015) or previous vaginal birth after cesarean (P<.001) and among those with higher Bishop scores (P<.001). Previous cesarean delivery for failed induction of labor and arrested labor were associated with a 56.0% (relative risk, 1.56 [95% confidence interval, 1.01-2.39]) and 90.0% (relative risk, 1.90 [95% confidence interval, 1.24-2.91]) increased risk of repeat cesarean delivery, respectively (relative risk, 1.56 [95% confidence interval, 1.01-2.39]). Cesarean delivery for malpresentation was associated with a lower risk of repeat cesarean delivery (relative risk, 0.51 [95% confidence interval, 0.27-0.89]).

CONCLUSION

Previous vaginal birth after cesarean and higher Bishop score predict the success of induction of labor after cesarean, whereas previous cesarean delivery for labor arrest or failed induction of labor increases the risk of repeat cesarean delivery in patients with unfavorable cervices. These findings may guide counseling and future research.