Mifepristone and misoprostol administered simultaneously versus 24 hours apart for abortion: a randomized controlled trial

Obstet Gynecol. 2007 Apr;109(4):885-94. doi: 10.1097/01.AOG.0000258298.35143.d2.


Objective: Mifepristone and oral misoprostol are typically used for medical abortion in women up to 49 days of gestation, with a 36- to 48-hour interval between the medications. Alternative routes of misoprostol administration allow for use beyond 49 days of gestation. We designed this randomized, noninferiority trial to compare the efficacy, adverse effects, and acceptability of misoprostol 800 mcg vaginally administered simultaneously with, or 24 hours after, mifepristone 200 mg orally for abortion in women up to 63 days of gestation.

Methods: The 1,128 participants swallowed mifepristone 200 mg and were then randomized to self-administer misoprostol intravaginally immediately in the office (group 1) or 24 hours later at home (group 2). Subjects returned for an evaluation, including transvaginal ultrasonography, 7+/-1 days after initiating treatment. Women who had not aborted were offered a second dose of misoprostol and returned for another evaluation in approximately 1 week. A phone contact was also attempted approximately 5 weeks after treatment. Treatment was considered a failure if a suction aspiration was performed for any indication.

Results: The complete abortion rate for group 1 (95.1%, 95% confidence interval [CI] 93.0-96.8%) was statistically noninferior to that for group 2 (96.9%, 95% CI 95.1-98.2%) (P=.003). The abortion rates between groups did not significantly differ by gestational age. Adverse effects were mostly similar, although nausea, diarrhea, and warmth or chills were significantly more common in group 1.

Conclusion: Mifepristone 200 mg and misoprostol 800 mcg vaginally used simultaneously is as effective for abortion as compared with regimens using a 24-hour dosing interval.

Clinical trial registration: ClinicalTrials.gov, www.clinicaltrials.gov, NCT00269568

Level of evidence: I.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial

MeSH terms

  • Abortifacient Agents, Nonsteroidal / administration & dosage*
  • Abortifacient Agents, Steroidal / administration & dosage*
  • Abortion, Induced / methods*
  • Drug Administration Schedule
  • Drug Therapy, Combination
  • Female
  • Humans
  • Mifepristone / administration & dosage*
  • Misoprostol / administration & dosage*
  • Pregnancy
  • Treatment Outcome


  • Abortifacient Agents, Nonsteroidal
  • Abortifacient Agents, Steroidal
  • Misoprostol
  • Mifepristone

Associated data

  • ClinicalTrials.gov/NCT00269568