Ovulation resumption after medical abortion with mifepristone and misoprostol

As an antiprogestin, mifepristone may have an impact on the return to ovulation in a manner that is not only attributable to its abortifacient activity. Our aim was to measure the time-to-ovulation in women who received mifepristone 200 mg orally and misoprostol 800 mcg vaginally for abortion up to 63 days of gestation.

This planned substudy was part of a multicenter randomized trial of mifepristone 200 mg followed immediately or 24 h later by misoprostol 800 mcg vaginally. Women who had successful expulsion of the gestational sac based on ultrasound examination 1 week after mifepristone treatment were enrolled. All subjects used nonhormonal contraception until study completion. Baseline serum progesterone (P) levels were drawn on day 8±1 after mifepristone administration and then twice weekly until the P level was >3 ng/mL, consistent with ovulation. The mean time-to-ovulation was calculated using interval censored regression to address the censoring due to participant discontinuation.

Fourteen (52%) of 27 enrolled women completed the substudy. The longest period of time that a subject who did not complete the study was followed was 29 days. Ovulation occurred 20.6±5.1 (range 8-36) days after mifepristone administration. Time-to-ovulation was not affected by participant age, gestational age, study arm, body mass index or presence or absence of human chorionic gonadotropin.

Return to ovulation following medical abortion with mifepristone and misoprostol occurs on average 3 weeks postabortion. Mifepristone 200 mg does not appear to have a lasting effect on ovarian function. Our results should be contextualized by the small sample size, although this is one of the larger studies on return to ovulation after abortion.