【摘要】 目的 探讨米非司酮用于紧急避孕的临床效果、最低有效剂量及对月经的影响、副反应及可接受性。方法 采用避孕失败或未保护性生活120h内要求紧急避孕的243例妇女随机分2组，研究组143例，对照组100例，分别单次口服米非司酮10mg和25mg，服药后嘱两组对象按期随访。以月经来潮为成功标准，观察其避孕效果、副反应、对月经的影响及药物可接受性情况。结果 采用DiXon方法计算，两组对象各有2例妊娠，均明显低于预期妊娠，其避孕有效率分别为84.40%和81.55%，组间差异无显著性(P>0.05)。两组副反应轻、无任何不良反应发生；对月经周期、经期与经量影响较小；经间期出血的发生率对照组明显高于研究组(15.38%、4.2%)，其发生与服药的时间有关，组间差异有极显著性﹙P<0.01﹚。对月经的影响，研究组更优于对照组。结论 米非司酮10mg是用于紧急避孕的简便、安全、有效的方法，值得临床推广。

    【关键词】 米非司酮；紧急避孕；月经周期

    【Abstract】 Objective To observe the effects of mifepristone on postcoital contraception and find out the minimum effective dose ， the effect on menstrual cycle， side effects and the treatment acceptability.Methods A total of 243 cases of clinical contraception failure or unprotected sexual intercourse within 120 hours which demanded postcoital contraception were only treated with different dose of oral mifepristone which was divided into two groups according to mifepristone dosage protocol : the treatment group of 10mg Mifepristone and the control group of 25mg. After treatment， two groups were flowed up until next menstruation or to be diagnosed as pregnancy ......