# Induction of Labor in Late-Term and Post-Term Pregnancies Using Double-Balloon Catheter for Cervical Ripening: Predictors of Prolonged Labor Across Four Combined Augmentation Protocols in a Retrospective Cohort Study

## TL;DR

This study examines how different methods of labor induction using a double-balloon catheter affect delivery times and outcomes in late-term pregnancies.

## Contribution

The study introduces a prediction model for timely delivery based on cervical changes and compares four DBC-based augmentation protocols.

## Key findings

- DBC combined with misoprostol had the shortest delivery interval but highest hyperstimulation risk.
- Post-ripening Bishop score change was the strongest predictor of timely delivery.
- Prolonged labor increased maternal and neonatal complications.

## Abstract

Background/Objectives: Induction of labor at ≥41 weeks with an unfavorable cervix is challenging. Comparative evidence for double-balloon catheter (DBC)-based augmentation protocols is limited. We aimed to estimate the frequency of prolonged labor, compare four DBC-based protocols, and identify predictors of timely vaginal delivery in the study population. Methods: This retrospective cohort study analyzed 709 women with singleton, cephalic pregnancies at ≥41 weeks and a Bishop score of ≤6 who achieved vaginal delivery following DBC-based induction at a tertiary referral center (2017–2026). The protocols comprised DBC alone or in combination with oxytocin, dinoprostone, or misoprostol. The primary outcome was vaginal delivery within 24 h of DBC insertion. Multivariable logistic regression and Kaplan–Meier analyses were performed, adjusting for maternal age, parity, body mass index, and post-ripening Bishop score changes. Results: Prolonged labor (≥24 h) occurred in 10.2% of vaginal deliveries and was associated with significantly elevated maternal infectious morbidity and adverse neonatal respiratory outcomes. The median induction-to-delivery interval was shortest with DBC plus misoprostol and longest with DBC plus dinoprostone (p < 0.001). Uterine hyperstimulation was most frequent with misoprostol (21.2% of cases). Post-ripening Bishop score change emerged as the strongest predictor of timely delivery (adjusted OR 4.72, 95% CI 2.99–7.43), whereas advancing maternal age reduced the odds of timely delivery (adjusted OR 0.65 per year, 95% CI 0.57–0.75). The prediction model demonstrated excellent discrimination (AUC = 0.924). Conclusions: In late-term and post-term DBC-based inductions, prolonged labor affected 10% of vaginal deliveries and substantially increased maternal and neonatal morbidity. DBC combined with misoprostol achieved the shortest delivery interval but carried the highest risk of hyperstimulation, whereas DBC combined with oxytocin offered the most favorable uterine activity profile. Post-ripening cervical reassessment, particularly changes in the Bishop score, enables evidence-based risk stratification and may guide the selection of individualized protocols.