【摘要】 目的　探讨无保护性生活后一定时间内采用低剂量米非司酮 (10mg与 2 5mg)紧急避孕是否具有相同的避孕效果。方法　在中国各地 10个计划生育研究中心和医院中进行双盲、随机的比较研究。符合条件并在无保护性生活 12 0h内要求紧急避孕的 30 5 2例妇女被随机分配于米非司酮 10mg或 2 5mg两组。 结果　在 30 5 2例妇女中失访 2 2例 ,有明确结果者 30 30例 ,服米非司酮 10mg者 15 16例 ,服米非司酮 12 5mg者 15 14例。每组各有 17例妊娠 ,妊娠率为 1 1%。与 10mg米非司酮的妊娠率相比 ,2 5mg组的相对危险度为 1 0 ,双侧检验 95 %可信限为 (0 5 11 95 )。两种剂量均可预防 85 % 86 %未经治疗的预期妊娠。若服药后再有无保护性生活 ,妊娠率几乎增加一倍。随着服药时间的延迟 ,效果有下降趋势。副反应不常见 ,并且很轻。结论　米非司酮 10mg用于 5d内紧急避孕是一种安全有效的方法。越早使用效果越好。更多还原

【Abstract】 Objective To compare the effects of mifepristone of different doses on emergency contraception. Methods 3 052 healthy women with regular menstrual cycle who visited the 10 family planning institutes and hospitals in Beijing, Shanghai, Shangdong, Sichuan, Tianjin, Guangdong, and Liaoning for emergency contraception within the period of 120 hours after a single act of unprotected sex were given a single dose of 10 mg or 25 mg mifepristone randomly and double-blindly. They were asked to record the vaginal hemorrhage that would occur and not to have unprotected sex until the next menstrual onset when they were followed up. The trial for a specific subject ended when she menstruated. If the menstruation was irregular or a specific subject failed to menstruate on time a blood or urine human chorionic gonadotropin (hCG) test was made. If the hCG test was negative, an appointment was made to follow up once one week later. If the hCG test was positive ultrasound examination was made to detect pregnancy. If the subject still failed to menstruate and the hCG test was still negative follow-up for this subject could be finished. Results Twenty-two of the 3 052 subjects were lost to follow up. Among the remaining 3 030 women 1 516 were in the 10 mg group and 1 514 in the 25 mg group. Seventeen pregnancies occurred in each group, with a pregnancy rate of 1.1% for both groups. The relative risk of pregnancy of treatment of 25 mg mifepristone in comparison with treatment of 10 mg mifepristone was 1.0 (95% CI: 0.51 ~ 1.95). Both doses prevented about 85% ~ 86% of the anticipated pregnancy if no measure had been adopted. The pregnancy rate nearly doubled in the women who had unprotected sex after treatment of mifepristone. The efficacy of mifepristone decreased along with the delay of mifepristone administration. Side effects were uncommon and mild. Delay of 7 days or more in the onset of next menstruation occurred in 9%~10% of the women. Conclusion Mifepristone of the dose of 10 mg is safe and effective for emergency contraception. Earlier administration is preferable, although the method can be used effectively up to five days after the unprotected sex. [更多还原