Six compared with 12 hours of Foley balloon placement for labor induction in nulliparous women with unripe cervices: a randomized controlled trial

BACKGROUND: Compared with a planned 12-hour placement of a double-balloon catheter, a planned 6-hour placement of a double-balloon catheter shortens the labor induction to delivery interval. The Foley catheter is low cost. Moreover, it has at least comparable effectiveness to the proprietary double-balloon labor induction devices. Of note, a 6-hour placement of a Foley balloon catheter in nulliparas has not been evaluated.OBJECTIVE: This study aimed to evaluate 6-vs 12-hour Foley balloon placement for cervical ripening in the labor induction of nulliparas. STUDY DESIGN: A randomized controlled trial was conducted at the Universiti Malaya Medical Centre from January 2022 to August 2022. Nulliparas aged >= 18 years, with a term, singleton pregnancy in cephalic presentation, with intact membranes, with reassuring fetal heart rate tracing, with an unripe cervix, and without any significant contractions, were recruited at admission for labor induction. Participants were randomized after successful Foley balloon insertion, for the balloon to be left passively in place for 6 or 12 hours and then removed to check for a ripened cervix. Amniotomy was performed once the cervix had ripened, followed by titrated oxytocin infusion to expedite labor and delivery. The primary out-come was the labor induction to delivery interval. The secondary outcomes were mostly from the core outcome set for trials on labor induction of labor trial reporting, such as change in the Bishop score after the intervention, use of an additional method for cervical ripening, time to delivery after double-balloon device removal, mode of delivery, indication for cesarean delivery, duration of oxytocin infusion, blood loss during delivery, presence of a third-or fourth-degree perineal tear, maternal infection, maternal satisfaction regional analgesia in labor, length of hospital stay, intensive care unit admission, cardiorespiratory arrest, need for hysterectomy. The neo-natal outcomes were Apgar score at 1 and 5 minutes, neonatal intensive care unit admission, cord pH, neonatal sepsis, fetal birthweight, birth trauma, hypoxic-ischemic encephalopathy, or need for therapeutic hypothermia. Data were analyzed using the t test, Mann-Whitney U test, chi-square test, and Fisher exact test, as appropriate for the data type.RESULTS: Overall, 240 women were randomized, 120 to each arm. The median labor induction to delivery intervals were 21.3 hours (inter-quartile range, 16.2-27.9) for the 6-hour balloon catheter placement and 26.0 hours (interquartile range, 21.5-30.9) for the 12-hour balloon catheter placement (P<.001). Of the secondary outcomes, for 6-vs 12-hour balloon catheter placement, the sequential use of additional cervical ripening agent (mostly Foley reinsertion) was 33 of 119 (27.5%) vs 17 of 120 (14.2%) (relative risk, 1.94; 95% confidence interval, 1.15-3.29; P=.011), Bishop score increase was 3 (interquartile range, 2.00-3.75) vs 3 (2.25-4.00) (P=.002), and the rate of recommendation to a friend was 83 of 118 (70.3%) vs 101 of 119 (84.9%) (relative risk, 0.83; 95% confidence interval; 0.72-0.95; P=.007), respectively. Cesarean delivery rates were 52 of 119 (43.7%) for the 6-hour balloon catheter placement and 64 of 120 (53.3%) for the 12-hour balloon catheter placement (relative risk, 0.82; 95% confidence interval, 0.63-0.07; P=.136), and maternal satisfaction scores (0-10 numerical rating scale) were 7 (inter-quartile range, 6-9) for the 6-hour balloon catheter placement and 7 (interquartile range, 7-9) for the 12-hour balloon catheter placement (P=.880). CONCLUSION: Compared with a planned 12-hour Foley balloon catheter placement, a planned 6-hour Foley balloon placement shortens the time to birth, despite less cervical ripening at Foley balloon catheter removal and more additional cervical ripening agent use. However, the 6-hour balloon catheter placement was less likely to be recommended to a friend than the 12-hour balloon catheter placement.