Expanded clinical trial of emergency contraception with 10 mg mifepristone

We conducted a clinical single-arm trial to evaluate the effectiveness of 10 mg mifepristone for emergency contraception (EC) in a large population in China. The participating centers were 31 family-planning clinics and hospitals in the following 19 provinces or municipalities in China: Beijing, Shanghai, Tianjin, Harbin, Changchun, Shengyang, Shijiazhuang, Zhengzhou, Taiyuan, Nanjing, Jinan, Hangzhou, Guangzhou, Wuhan, Changsha, Chongqing, Guiyang, Chengdu, Kunming. A total of 4945 women requesting EC within 120 h after a single act of unprotected intercourse were recruited and treated with 10 mg mifepristone. A total of 28 women were lost to follow-up, and 4917 women were included in the analysis, of whom, 69 became pregnant. The combined pregnancy rate was 1.4 [95% confidence interval (CI): 1.0-1.9] and the percentage of pregnancies prevented was 82.2% (95% CI: 77.5-86.2%). There was a significant inverse trend in pregnancy rate with body mass index that disappeared when adjusted for other variables. The pregnancy risk was double among nulliparous women compared to parous women (2.3% compared to 1.0%), and it increased by a factor of 1.5 when the treatment was administered at 25-48 h and at 49-72 h compared to administration within 24 h, although this association was not significant. The risk of pregnancy was higher if intercourse took place during the follicular or preovulatory phase of the cycle. Women having repeated intercourse after treatment without any contraceptive methods had a dramatic increase in the risk of pregnancy, while those who used contraceptives had similar risk to those without acts. Side effects were mild and present in only small proportions of women: nausea and vomiting in 9% and other side effects in 2-3%. Delay of menstruation of 7 days or more occurred in 6.5% of women. The expanded study confirmed the high efficacy and safety of 10 mg mifepristone for EC.