A randomized clinical trial of mifepristone (RU486) for induction of delayed menses: efficacy and acceptability.

Mifepristone (RU486) should be useful for inducing menstrual bleeding in women with menses delayed up to 10 days. We evaluated this potential use for "menstrual regulation" in a randomized clinical trial with 16 women, half of whom received a single 600 mg dose and half of whom received a placebo. Four of eight women in each treatment group proved to be pregnant. Seven of eight who received mifepristone were not pregnant at two-week follow-up, in contrast to four of eight who received the placebo (p = 0.15). Mifepristone may hold promise for "menstrual regulation" for women who do not have access to medical confirmation of pregnancy or who choose not to have this determination made.