24-Hour Compared With 12-Hour Mifepristone–Misoprostol Interval for Second-Trimester Abortion: A Randomized Controlled Trial [ID 2683386]

INTRODUCTION: We aimed to compare 24- and 12-hour mifepristone to misoprostol intervals for second-trimester medical abortion. METHODS: This was a prospective randomized controlled trial. Women were allocated to receive mifepristone either 24 or 12 hours before misoprostol administration. The primary outcome was time from mifepristone administration to fetal expulsion and from first misoprostol administration to fetal expulsion. RESULTS: Eighty women were enrolled between July 2020 and June 2023, 40 women per group. Baseline characteristics were comparable between groups. Median time from mifepristone to fetal expulsion was 33.0 and 24.5 hours in the 24- and 12-hour interval groups, respectively ( P <.001). Median time from first misoprostol dose to fetal expulsion was 9.5 and 12.5 hours in the 24- and 12-hour interval arms, respectively ( P =.028). At 12 hours from misoprostol administration, 25 (62.5%) and 18 (45.0%) of women in the 24- and 12-hour arms completed abortion ( P =.178). At 24 hours from misoprostol administration, 36 (90.0%) and 30 (75.0%) in the 24- and 12-hour arms had complete abortion ( P =.139). Need for additional medical and/or surgical treatment for uterine evacuation were comparable between groups. Pain scores, side effects, and satisfaction levels were similar in both groups. CONCLUSION: A 12-hour mifepristone-to-misoprostol regimen for medical abortion in the second trimester provides an 8.5-hour shorter mifepristone-to-fetal-expulsion rate compared with the 24-hour interval. However, misoprostol-to-fetal-expulsion time is 3 hours longer in the 12-hour interval regimen. Medical regimen success rate, side effects, and satisfaction levels are also similar. These findings can aid in shared decision-making prior to medical abortion in the second trimester.