Labor induction in women at term with mifepristone (RU 486) : a double-blind, randomized, placebo-controlled study

120 pregnant women with amenorrhea ranging from 37.5-41.4 weeks who had clear clinical indications for labor induction were enrolled in a double-blind placebo-controlled study. They were randomly divided into 2 groups of 60 each to receive either 200 mg of mifepristone (RU 486; Roussel-Uclaf Paris France) orally for 2 days (days 1 and 2) of a 4-day observation period or a placebo with labor induction planned for day 4. 8 patients had to be excluded because they required Cesarean Section for Fetal distress or maternal complications. Those with favorable cervical conditions had rupture of membranes oxytocin infusion and epidural anesthesia. 45 needed cervical maturation with 2.5 mg vaginal tablets of prostaglandin (PG) E2 every 6 hours until cervical maturation on day 4 13 of whom had received mifepristone and 32 of whom had been given placebo (P < .001). 41 subjects entered spontaneous labor 31 treated with mifepristone and 10 in the control group (P < .001). 13 women treated with mifepristone and 13 who had taken the placebo had mature cervices sufficient for classic labor induction with oxytocin and amniotomy. Patients who delivered vaginally needed much less oxytocin when treated with mifepristone and the mean interval between day 1 and the start of labor was also significantly shorter. Spontaneous labor occurred on day 1 for 8 patients after only 1 tablet of mifepristone or day 2 for 10 and on day 3 for 7. Mifepristone was found to be a safe efficient and suitable agent for induction of labor in women at term.