Medical abortion in the late first trimester: a systematic review

To describe the efficacy, safety, and acceptability of medical abortion in the late first trimester.

We searched PubMed and Cochrane databases for articles in any language that examined the success of medical abortion at gestational ages (>63 to≤84 days gestation). We sought articles that compared: medical abortion with surgical abortion at this gestational age, combination mifepristone and misoprostol and/or misoprostol alone); different dosages of misoprostol; different routes of misoprostol administration; frequency of dosing; and location of medical abortion (in health care facility vs. outpatient management). Our primary outcome was complete abortion. Data was independently abstracted by two authors, graded for evidence quality, and assessed for risk of bias.

The search strategy returned 3384 articles, nine of which met inclusion criteria. Medical abortion, as compared with surgical abortion, was effective in the late first trimester (94.6% versus 97.9% complete abortion). A combined regimen of mifepristone and misoprostol was significantly more effective than misoprostol alone (90.4 versus 81.6% complete abortion). Complete abortion rates for all regimens investigated ranged from 78.6% to 94.6%. Success rates were higher with repeat dosing of misoprostol both in combination regimens and alone, and with vaginal compared with oral administration for repeat dosing.

A limited body of evidence indicates a range of efficacy of medical abortion in the late first trimester and highlights the need for well-designed trials in this gestational age range.

This review highlights the need for research focused on the late first trimester to strengthen the body of evidence. The available evidence is limited but offers reassurance that adverse events are rare for later first trimester abortion. Importantly, new research demonstrates that efficacy remains unchanged in the 10th gestational week regardless of whether the medication is taken in a facility or at a woman's home.