title: [Effects of mifepristone of different doses on emergency contraception, a randomized double-blind study].
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% approximately 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: National Research Institute for Family Planning, Beijing 100081, China. xiaobl@public.bta.net.cn
authors.forename: Bi-lian
authors.initials: BL
authors.lastname: Xiao
authors.forename: H
authors.initials: H
authors.lastname: von Hertzen
authors.forename: Heng
authors.initials: H
authors.lastname: Zhao
authors.forename: Gilda
authors.initials: G
authors.lastname: Piaggio
authors.forename: Shang-chun
authors.initials: SC
authors.lastname: Wu
authors.forename: Jun
authors.initials: J
authors.lastname: Huang
authors.forename: Li-ju
authors.initials: LJ
authors.lastname: Weng
authors.forename: Li-jia
authors.initials: LJ
authors.lastname: Zhang
authors.forename: Li-nan
authors.initials: LN
authors.lastname: Cheng
authors.forename: Fang-ming
authors.initials: FM
authors.lastname: Ren
authors.forename: Chang-hai
authors.initials: CH
authors.lastname: He
authors.forename: You-lun
authors.initials: YL
authors.lastname: Gui
authors.forename: Zhen-jia
authors.initials: ZJ
authors.lastname: Huang
authors.forename: Zhen-wu
authors.initials: ZW
authors.lastname: Lei
authors.forename: Ming-hui
authors.initials: MH
authors.lastname: Zhu
authors.forename: Li-juan
authors.initials: LJ
authors.lastname: Song
authors.forename: Xiao-ming
authors.initials: XM
authors.lastname: Cao
authors.forename: Rong-fen
authors.initials: RF
authors.lastname: Wang
authors.forename: Wan-hua
authors.initials: WH
authors.lastname: Ding
authors.forename: Qing-ming
authors.initials: QM
authors.lastname: Mei
authors.forename: Feng-xian
authors.initials: FX
authors.lastname: Ni
authors.forename: Ning
authors.initials: N
authors.lastname: Zheng
mesh_terms: D000328:Adult; D003267:Contraception / Q000379:methods*; D003283:Contraceptives, Postcoital, Synthetic / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004630:Emergencies; D005260:Female; D006801:Humans; D015735:Mifepristone / Q000008:administration & dosage*; D011247:Pregnancy
chemical_list: D003283:Contraceptives, Postcoital, Synthetic; D015735:Mifepristone