Single Lower-Dose Medical Abortion Equally Effective

Medical abortions using mifepristone 200 mg followed by vaginal misoprostol are 95% to 98% effective. A pilot study at Boston University suggests that mifeprestone 100 mg plus misoprostol at the same time is equally effective.

Researchers led by Nathalie Kapp, MD, enrolled 40 women who wanted a medical abortion and had pregnancies up to 56 menstrual days by ultrasound exam. Women in the study were given half of a standard 200-mg mifepristone tablet orally and 800 mcg of misoprostol placed vaginally by a clinician. All of the women had follow-up exams 2 to 7 days later and a phone call after 3 weeks to evaluate symptoms and satisfaction. The 95% confidence level for matching the 95% success rate produced by higher-dose studies requires a confidence interval of 88% to 100% for 40 subjects.

One woman was lost to follow-up and the other 39 had visits as scheduled. Four women had uterine aspiration, one for nonviable pregnancy, two for incomplete abortion, and one for continuing pregnancy. The median time from medication to passage of pregnancy was 7 hours with a mean of 13.8 bleeding days. Nearly all of the women, 92%, strongly preferred taking both medications at the same time.

Kapp N, Borgatta L, Ellis SC, Vragovic O, Stubblefield P. Simultaneous low-dose mifepristone and vaginal misoprostol for medical abortion: How low can you go? Obstet Gynecol. 2005;105(4 suppl):57S.