Emergency contragestion

Abstract

The recent availability of mifepristone (RU 486), a competitive progesterone antagonist capable of interrupting pregnancy in the 1st month, offers a new method for the medical termination of pregnancy. This study evaluated the efficacy and safety of RU 486 as a contragestive agent in 100 healthy pregnant women who applied for abortion within 10 days of the expected onset of the missed menstrual period. The women were randomly assigned to 1 of 3 different regimens of oral RU 486: 50 mg twice/day for 4 days (group 1), 50 mg 3 times/day for 4 days (group 2), and 400 mg once/day for 2 days (group 3). Uterine bleeding occurred in all study subjects and began within 4 days of the 1st dose of RU 486. 85 of the 100 subjects were considered to have had a complete abortion. This included 28/34 patients in group 1, 23/26 patients in group 2, and 34/40 patients in group 3. The mean duration of uterine bleeding was 11.6 + or - 5.8 days in the women with complete abortion. 18% of these women experienced heavy bleeding for 2-6 days and 26% reported painful uterine contractions exceeding normal menstrual pain. Plasma beta human chorionic gonadotropin (hCG) levels were relatively constant during RU 486 treatment, but dropped dramatically 2-4 days later. Plasma P and E2 levels paralleled plasma beta hCG levels, suggesting that the luteolysis was 2ndary to the decrease of beta hCG after trophoblast separation. The high frequency of complete abortion in this study (85%) compared to other studies suggests that the efficacy of RU 486 increases with shorter length of gestation.