Induction of Labor in Women with Previous Cesarean Section and Unfavorable Cervix: A Retrospective Cohort Study

Background: The efficacy and safety of a cervical ripening balloon (CRB) in women with a previous cesarean section (CS) and unfavorable Bishop score are still controversial. Methods: A retrospective cohort study was performed across six tertiary hospitals from 2015 to 2019. Women with one previous transverse CS, singleton cephalic term pregnancy and BS < 6 were included if submitted to labor induction with a CRB. The main outcome was the rate of vaginal birth after cesarean (VBAC) after CRB ripening. Secondary outcomes were abnormal composite fetal and maternal outcomes. Results: Of the 265 women included, 57.3% had successful vaginal birth. Augmentation improved vaginal delivery (32.2% vs. 21.2%). Intrapartum analgesia was associated with an increased VBAC rate (58.6% vs. 34.5%). Maternal BMI >= 30 and age >= 40 years increased emergency CS rate (11.8% vs. 28.3% and 7.2 vs. 15.9%). Composite adverse maternal outcome occurred in 4.8% of CRB group women and increased to 17.6% when associated with oxytocin. Uterine rupture occurred in one case (0.4%) in the CRB-oxytocin group. Poorer fetal outcome occurred after emergency CS, if compared to successful VBAC (12.4% vs. 3.3%). Conclusions: In women with a previous CS and unfavorable Bishop score, induction of labor with a CRB can be considered safe and effective.