Objectives:To study the efficacy of
mifepristone and/or
anordrin for emergency contraception( EC).Design:A randomized clinical
trial.Setting:Outpatients clinic of Chaoyang Hospital in Beijing. Subjects:139 healthy women with history of unprotected intercourse or contraceptive failure were re-cruited from February to April 1995.All had regular mentrual cycles and attended the clinic within 72 hours after,intercourse. Methods: Women were randomly allocated into 3 groups. In group I,
mifepristone 25mg was given and the same dose was repeated 12 hours later with a total dose of 50mg(n=46 ).In group II,
Anordrin 7.5mg was given twice at 12 hours interval(n=46).Group III,both mifepristone 25mg and anordrin 7.5mg were given once(n=47).Women were asked to record their bleeding patterns as well as any unexpected adverse effects. The pregnancy rates were calculated by Dixon’s method according to the expected pregnancy proba-bility on specific cycle day. Serum estradiol,LH and progesterone were determined in 45 women of the 3 groups before and after treatment, and transvaginal ultrasonography were carried out at the same time. Results:The contraceptive effective rates were 100% in both group I and III,and 36.7%(2/46)in group II,which was close to the expected pregnancy 3.163.Menstruation was postponed in 7 women(15.2%)in group I.4 women(8.7%)in group II and II (23.4%)in group III.Side effects including nausea and vomiting were reported as 4.3%,15.2%.and 6.4% in the 3 groups respectively,and were not signifi-cantly different.Hormone assays showed 3 patterns of changes i.e.anovulatory,periovulatory and postovu-latory,and were confirmed by B ultrasound.Conclusion:Low dose mifepristone or in combination with anordrin given within 72 hours after unpro-tected intercourse was effective for emergency contraception.