紧急避孕药(Emergency contraceptives)是一类能够提供妇女在无保护性交或使用其他避孕措施失败后安全地预防非意愿妊娠的应急性口服避孕药[1]。目前,世界卫生组织推荐的左炔诺孕酮用于紧急避孕的剂量方案:在无保护性交后72 h内尽可能早的一次口服1.5 mg或相隔12 h各服1剂0.75 mg。左炔诺孕酮此两种剂量方案的紧急避孕疗效和安全性相当[2-3],均可减少60%~93%的 Emergency contraceptives are a type of acute oral contraceptive that provides safeguards against unwanted pregnancies in women who fail unprotected intercourse or other forms of contraception [1]. Currently, levonorgestrel recommended by the World Health Organization is used in the emergency contraception dosage regimen: as soon as possible after an unprotected intercourse for 1.5 mg once as early as possible or as a 0.75 mg dose for one dose after 12 h. Levonorgestrel efficacy and safety of these two doses of emergency contraception quite a [2-3], can be reduced by 60% to 93% of