DETERMINANTS OF PROLONGED INDUCTION-TO DELIVERY INTERVAL FOLLOWING MISOPROSTOL INDUCTION IN WOMEN WITH PRELABOR RUPTURE OF MEMBRANES

Abstract

Background: Prelabor rupture of membranes (PROM) frequently requires labor induction to reduce the risks associated with prolonged membrane rupture. Although misoprostol is an effective method for cervical ripening and labor induction in women with PROM, the duration of induction varies considerably between individuals. Identifying factors associated with prolonged induction-to-delivery interval may improve pre-induction counseling and clinical planning. This study aimed to determine the clinical and obstetric factors associated with prolonged induction-to-delivery interval among women with PROM undergoing misoprostol induction. Methods: A single-center observational study was conducted among women with PROM undergoing misoprostol-induced labor at the study hospital between January and June 2022. Baseline maternal and obstetric characteristics, including maternal age, parity, gestational age, duration of membrane rupture before induction, and cervical favorability assessed using the Bishop score, were recorded. The primary outcome was induction-to delivery interval, with prolonged induction defined according to the study protocol as an interval exceeding 18 hours. Associations between baseline characteristics and prolonged induction were assessed using appropriate univariable and multivariable statistical analyses. Induction-to-delivery interval was additionally evaluated as a continuous outcome. Results: A total of 150 women were included in the analysis. Women with prolonged induction were more likely to have lower parity and a lower baseline Bishop score than those with shorter induction intervals. In multivariable analysis, increasing parity was associated with lower odds of prolonged induction, while a higher Bishop score was independently associated with a shorter induction-to-delivery interval. In the continuous analysis, both parity and Bishop score remained significantly associated with induction duration. Maternal age, gestational age, and duration of membrane rupture before induction were not independently associated with prolonged induction. Conclusion: Among women with PROM undergoing misoprostol induction, lower parity and unfavorable cervical status at the initiation of induction were important determinants of a prolonged induction-to-delivery interval. Assessment of parity and Bishop score before induction may help clinicians anticipate induction duration and provide more individualized counseling. Further multicenter prospective studies are warranted to validate these findings and develop clinically useful prediction models for prolonged induction.