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

Abstract

Planned 6 versus 12 hours placement of the double-balloon catheter shortens the induction to delivery interval. The Foley catheter is low-cost and has at least comparable effectiveness to the proprietary double balloon labor induction devices. 6 hours placement with the Foley balloon in nulliparas has not been evaluated. To evaluate 6 vs 12 hours Foley balloon placement for cervical ripening in the labor induction of nulliparas. A randomized controlled trial was conducted in University Malaya Medical Center from January 2022 to August 2022. Nulliparas aged 18 years or above, with a term, singleton pregnancy in cephalic presentation, intact membranes, reassuring fetal heart rate tracing, unripe cervix, 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, 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. Primary outcome was the induction to delivery interval. Secondary outcomes were mostly from the core outcome set (CROWN) for induction of labor trial reporting1 such as change in Bishop score after intervention, use of additional method for cervical ripening, time to delivery after double-balloon device removal, mode of delivery, indication for cesarean section, duration of oxytocin infusion, blood loss during delivery, presence of third- or fourth-degree perineal tear, maternal infection, maternal satisfaction regional analgesia in labor, length of hospital stay, Intensive Care Unit (ICU) admission, cardiorespiratory arrest, need for hysterectomy. The neonatal outcomes are Apgar score at 1 and 5 minutes, neonatal ICU (NICU) admission, cord pH, neonatal sepsis, fetal birth weight, birth trauma, hypoxic ischemic encephalopathy or need for therapeutic hypothermia. Data were analyzed with the t-test, Mann-Whitney U test, Chi square test and Fisher exact test as appropriate for the data type. 240 women were randomized, 120 to each arm. The induction to delivery interval was median[interquartile range] 21.3[16.2-27.9] vs 26.0[21.5-30.9] hours P<0.001 for 6 vs 12 hours placement respectively. Of the secondary outcomes, the sequential use of additional cervical ripening agent (mostly Foley reinsertion) was 33/19(27.5%) vs 17/120(14.2%) RR 1.94 95% CI 1.15-3.29 p=0.011, Bishop score increase was 3[2-3.75] vs 3[2.25-4] p=0.002 and rate of recommendation to a friend was 83/118(70.3%) vs 101/119(84.9%) RR 0.83 95% CI 0.72-0.95 p=0.007 for 6 vs 12 hours placement respectively. Cesarean delivery rate was 52/119(43.7%) vs 64/120(53.3%) RR 0.82 95% CI 0.63-0.07 p=0.136 and maternal satisfaction score (0-10 numerical rating scale) was 7[6-9] vs 7[7-9] p=0.880 for 6 vs 12 hours respectively. Planned 6 vs 12 hours Foley balloon placement shortens time to birth despite less cervical ripening at Foley removal and more additional cervical ripening agent use. However, 6 hours placement was less likely to be recommended to a friend.