Mifepristone 24 hours before misoprostol for second-trimester abortion cuts induction time by 3 hours


Raanan Meyer, MD, shares the results and takeaways from his ACOG 2024 study on a 24-hour compared with 12-hour mifepristone-misoprostol regimen for second-trimester abortion, including the impact on patient satisfaction.

Shortening total abortion time could drastically improve the patient experience and contribute to shorter hospitalizations, lowered infection risks, more streamlined health care delivery, and an improved psychological impact. Additionally, providing patients with all their options when it comes to medical abortion is paramount in order to facilitate shared decision-making.

Second-trimester abortion is currently performed with use of the competitive progesterone receptor antagonist mifepristone and repeat doses of misoprostol, and both national and international guidelines currently recommend a 24- to 48-hour mifepristone-misoprostol interval.1 But there is some evidence to support a shorter interval between the two without compromise to overall induction time.

In an oral abstract presentation at the American College of Obstetricians and Gynecologists 2024 Annual Clinical & Scientific Meeting in San Francisco, California, held from May 17-19, 2024, a team of investigators compared 12-hour and 24-hour mifepristone-to-misoprostol intervals via a randomized controlled trial.

The group, led by Raanan Meyer, MD, instructor of obstetrics and gynecology at Cedars Sinai, sought to evaluate time from first misoprostol dose to abortion, or induction time. They also monitored total abortion time, or time from first mifepristone does to abortion, as well as fetal expulsion percentages at intervals, side effects, pain, and patient satisfaction scores.

The use of mifepristone 24 hours before a misoprostol regimen for second trimester abortion resulted in a shorter induction time by 3 hours compared to taking mifepristone 12 hours before (P = 0.028), investigators found. The median induction time in the 24-hour arm was 9.5 hours (95% CI 10.3-17.8) compared with 12.5 hours in the 12-hour group (95% CI 13.5-20.2). According to Meyer, there were no significant differences in patient satisfaction or adverse events between the arms.

“The results of this study can provide information to help patients in choosing the medication regimen that will most likely align with their goals, their preferences, their needs,” Meyer told Contemporary OB/GYN in an interview. “Overall, the results can help provide more patient-centered care.”


  1. ACOG Practice Bulletin No. 135: Second-trimester abortion. Obstet Gynecol. Jun 2013;121(6):1394-406. doi:10.1097/01.AOG.0000431056.79334.cc
  2. Meyer R, Toussia-Cohen S, Shats M, Segal O, Blumenthal P, Mashiach R. Twenty-Four compared with 12-hour mifepristone-misoprostol interval for second trimester abortion- a randomized controlled trial. Presented at: The American College of Obstetricians and Gynecologists 2024 Annual Clinical & Scientific Meeting. San Francisco, CA. May 17-19, 2024.
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