Outpatient cervical ripening with Foley balloon or mifepristone: Insights into the time taken to reach the active phase of labor.

To estimate the median time elapsed between the start of cervical ripening and the diagnosis of the active phase of labor, according to maternal and pregnancy characteristics, in low-risk pregnancies submitted to outpatient cervical ripening with a Foley balloon catheter or oral mifepristone. This was a secondary analysis of a randomized controlled trial conducted in a European tertiary level hospital, including 101 women with singleton pregnancies, cephalic presentation, and an unfavorable Bishop score. Participants were randomized to receive an intracervical Foley balloon catheter or oral mifepristone (200 mg). The main outcome evaluated was the median time elapsed between the start of the cervical ripening process and the active phase of labor. Cox proportional hazards regression was used to estimate hazard ratios (HR) for factors influencing progression to active labor. The median interval from the start of cervical ripening to the active phase of labor was 34.3 h (interquartile range [IQR]: 25-50.1). Previous pregnancy (HR: 1.74; 95% CI: 1.18-2.58), gestational age (HR: 1.34; 95% CI: 1.04-1.73), and a permeable cervix at baseline (HR: 2.28; 95% CI: 1.44-3.63) were significantly associated with progression to the active phase of labor. Foley balloon and mifepristone showed comparable median times to the active phase of labor, whereas much shorter durations were observed in those with a permeable cervix at baseline. Maternal age, gestational age, parity, and permeable cervix at baseline significantly influence the time interval from the start of cervical ripening to the active phase of labor. These may constitute a useful set of information for individualized patient counseling, allowing better alignment of expectations and increased satisfaction with the induction process.