Background: 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.
Study design: 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.
Results: 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.
Conclusions: 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.
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