Cervical ripening with mifepristone before labor induction: A randomized study

Objective: To determine the efficacy and safety of mifepristone for cervical ripening in post-term pregnancies. Methods: Women with post-term pregnancies and Bishop scores less than 6 were assigned randomly to mifepristone (41 patients) or placebo (42 patients). Mifepristone was given orally in a dose of 400 mg. Efficacy was assessed by change in the Bishop score within 48 hours after treatment; a score of 6 or greater was considered a "strict" success. An "extended" success rate was defined, including all patients with scores of at least 6 or those who delivered within 48 hours of treatment. Antenatal safety was assessed by fetal heart rate testing before and throughout labor. Neonatal safety was assessed by Apgar score, arterial or venous pH of cord blood, and blood glucose level during the first 48 hours. Analysis used Student t test for continuous variables, Kruskal-Wallis test for ordinal data, and chi(2) for categoric variables. Results: Strict success was achieved in 10 of 18 mifepristone patients (55%) evaluated for Bishop score an day 2 versus 8 of 29 placebo patients (27.5%) (P = .004). Extended success was achieved in 33 mifepristone patients (80.5%) and 21 placebo patients (50.0%) (P = .004). There were no statistical differences with regard to number of cesareans or fetal and neonatal safety. Conclusion: Mifepristone proved effective for cervical ripening and reduced the time to delivery compared with placebo, but it did not improve the rate of cesarean. Our study did not include enough pregnancies to reach conclusions about fetal or neonatal safety. (Obstet Gynecol 1998; 92:487-92. (C) 1998 by The American College of Obstetricians and Gynecologists.).