Outcomes of mifepristone usage for cervical ripening and induction of labour in full-term pregnancy. Randomized controlled trial

Abstract

Objective: The most commonly used approved indications for mifepristone in obstetrics include: termination of early pregnancy, cervical dilatation prior to abortion, labour induction in case of fetal death in utero. Fewer studies have been conducted on the effect of mifepristone on cervical ripening and induction of labour in term pregnancy with a live fetus. The aim of our study was to evaluate efficacy and safety of mifepristone use for cervical ripening and induction of labour versus expectant management in full-term pregnancy.

Study design: Randomized controlled trial. 149 women were randomized, 74 for cervical ripening and induction with mifepristone (200mg orally at the moment of enrollment and, if applicable, second dose after 24h), 75 - expectant management. Primary outcomes: gain in Bishop Score within 24 and 48-h of mifepristone; number of women going into spontaneous labor within 24, 48 and 72-h of mifepristone; rate of failed induction or expectant management.

Secondary outcomes: enrollment-induction to delivery interval; mode of delivery; requirement of oxytocin augmentation, neonatal outcomes.

Results: After 48h from enrollment mean gain in Bishop score was 2.58±1.33 in the induction group and 1.15±0.97 in the expectant group (<0.001). Failed management rate was 5.41% and 2.67%, respectively. Significantly more mifepristone treated women had labour within 24, 48 and 72h from enrollment (RR 15.20 CI 95% 2.06-112.18; RR 6.08 CI 95% 2.73-13.57; RR 2.14 CI 95% 1.04-4.42) (p<0.05). Enrollment-induction to delivery interval was significantly shorter in mifepristone group: 2.69±2.06 vs 3.77±1.86days (p<0.001). Premature rupture of membranes, meconium-stained amniotic fluid were more common in expectant management, but regional analgesia and cephalopelvic disproportion - in induction group. There were no differences in mode of delivery, requirement of oxytocin augmentation and main neonatal outcomes.

Conclusion: Mifepristone was efficient on inducing cervical ripening and labour in full-term pregnancy. There were no significant difference in main maternal and neonatal outcomes between mifepristone use and expectant management. There were no serious adverse side effects of mifepristone, but there were some features of the course of labor, like more painful uterine contractions and trend of higher rate of cephalopelvic disproportion, that might be directly related to the mifepristone action.

Keywords: Delivery; Induction of labour; Maternal outcomes; Mifepristone; Neonatal outcomes.