Short-term efficacy and safety of early medical abortion in Japan: A multicenter prospective study.

Purpose: To evaluate the short-term efficacy and safety of a combined mifepristone-misoprostol regimen in individuals seeking medical abortion at up to 63 days of gestational age.

Methods: This open-label, multicenter, prospective study evaluated the short-term efficacy and safety of medical abortion, with the primary outcome being the abortion success rate 24 h after misoprostol administration. The participants received 200 mg of mifepristone orally and 800 μg of misoprostol buccally in the hospital/clinic 36-48 h later. Bleeding and lower abdominal pain, which are the main symptoms associated with medical abortion, were recorded.

Results: The abortion success rate was 93.3% (95% confidence interval [CI]: 87.3-97.1%) within 24 h of misoprostol administration, 63.3% (95% CI: 54.05-71.94%) within 4 h, and 90.0% (95% CI: 83.18-94.73%) within 8 h. The median time from misoprostol administration to a successful abortion was 3.93 h. Bleeding was most commonly observed 0-4 h prior to the confirmation of gestational sac (GS) expulsion. The most intense lower abdominal pain occurred 0-1 h before the confirmation of GS expulsion.

Conclusion: The combined regimen of mifepristone and buccal misoprostol for medical abortion showed short-term efficacy and a favorable safety profile.