Transcervical Foley Balloon Plus Vaginal Misoprostol versus Vaginal Misoprostol Alone for Cervical Ripening in Nulliparous Obese Women: A Multicenter, Randomized, Comparative-Effectiveness Trial

Abstract

Objective Nulliparous obese women are at increased risk of labor induction and cesarean delivery (CD). We sought to determine whether the combination of a transvaginal Foley balloon plus misoprostol prostaglandin E1 (PGE1) is superior to misoprostol alone in reducing the risk for CD.

Study Design We undertook a multicenter, open-label, comparative-effectiveness randomized clinical trial of nulliparous obese women with unfavorable cervix (Bishop's score ≤ 6) undergoing labor induction from January 2016 to June 2018 at three tertiary centers. Those at <32 weeks' gestation, premature rupture of membranes, stillbirth, and major fetal anomalies were excluded. Women were randomized 1:1 to either a combination of Foley balloon and misoprostol or misoprostol alone. Once Bishop's score was >6, further management was deferred to treating physicians. Primary outcome was the rate of CD. Secondary maternal outcomes included duration of induction-to-delivery interval, occurrence of tachysystole, clinical chorioamnionitis, need for operative vaginal delivery, as well as a composite of maternal morbidity (postpartum endometritis, surgical-site infection, venous thromboembolism, need for transfusion, intensive care unit admission, and maternal death). Secondary neonatal outcomes included need for neonatal intensive care unit admission, transient tachypnea of the newborn, respiratory distress syndrome, meconium aspiration syndrome, culture-proven sepsis, neonatal seizures, and a composite of neonatal morbidity (Apgar's score ≤ 7 at 5 minutes, umbilical artery cord pH ≤ 7.10, birth injury, perinatal death). With the rate of CD rate being 53% at Children's Memorial Herman Hospital among nulliparous obese women who underwent induction of labor at ≥32 weeks and met our inclusion criteria; 250 women (125 women per group) were required to answer the study question. All analyses were by intention to treat.

Results Of the 236 women randomized, 113 (48%) were allocated to group 1 (combined Foley and PGE1) and 123 (52%) to group 2 (PGE1 alone). The rate of CD was similar between the groups (45 vs. 43%, p = 0.84, relative risk [RR]: 1.03, 95% CI: 0.75–1.42). There was no difference in the occurrence of tachysystole that resulted in fetal heart rate abnormalities between the groups (8.8 vs. 16.2%, p = 0.09, RR: 0.54, 95% CI: 0.27–1.11). The total duration of the induction-to-delivery interval was also similar between the groups (24.8 ± 13.8 vs. 24.5 ± 14.0 hours, p = 0.87) regardless of the mode of delivery. No differences were seen in the indications for CD and secondary maternal or neonatal outcomes.

Conclusion In this trial of nulliparous obese women undergoing labor induction, cervical ripening with combined Foley balloon and PGE1 resulted in similar CD rates than ripening with vaginal PGE1 alone.

Key Points

• Nulliparous obese women are at increased risk for cesarean delivery.

• Combined intravaginal misoprostol-Foley balloon versus misoprostol alone resulted in similar rates of cesarean delivery.

• Further research is warranted to determine the optimal cervical ripening strategy in this population.

Keywords

nulliparous - induction of labor - obese - Foley - misoprostol

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