Early pregnancy termination with mifepristone and misoprostol in the United States

N Engl J Med. 1998 Apr 30;338(18):1241-7. doi: 10.1056/NEJM199804303381801.


Background: Mifepristone and a prostaglandin have been used successfully to terminate pregnancy in Europe and China. We report the results of a large U.S. study of mifepristone and misoprostol in women with pregnancies of up to nine weeks' duration.

Methods: We administered 600 mg of mifepristone and then 400 microg of misoprostol two days later to 2121 women seeking termination of their pregnancies at 17 centers. The women were observed for four hours after the administration of misoprostol and returned on day 15 for final assessment.

Results: Two thousand fifteen women completed the final assessment. Among them, pregnancy was terminated in 762 of the 827 women pregnant for < or =49 days (92 percent), 563 of the 678 women pregnant for 50 to 56 days (83 percent), and 395 of the 510 women pregnant for 57 to 63 days (77 percent) (P<0.001). Termination occurred within 4 hours after the administration of misoprostol in 49 percent of the women and within 24 hours in 75 percent. Failures, defined as cases requiring surgical intervention for medical reasons or because the patient requested it, the abortion was incomplete, or the pregnancy was ongoing, increased with increasing duration of pregnancy. The largest increase was in failures representing ongoing pregnancy, which increased from 1 percent in the < or =49-days group to 9 percent in the 57-to-63-days group (P<0.001). Abdominal pain, nausea, vomiting, diarrhea, and vaginal bleeding also increased with advancing gestational age. Two percent of the women in the < or =49-days group, as compared with 4 percent in each of the other two groups, were hospitalized, underwent surgical interventions, and received intravenous fluids (P=0.008).

Conclusions: This mifepristone-misoprostol regimen is effective in terminating pregnancies, especially in women with pregnancies of 49 days' duration or less.

PIP: The availability of medical abortion in the US and elsewhere could lead to greater access to safer abortion services. This study assessed the capability of mifepristone (600 mg) and misoprostol (400 mcg 2 days later) to terminate pregnancies of up to 63 days' duration. Enrolled were 2121 US women recruited from 17 Planned Parenthood, university hospital, and free-standing abortion clinics. Among the 2015 women who returned for the follow-up visit at day 15, the rates of pregnancy termination were 92% in women with pregnancies of durations of 49 days or under, 83% in the 50-56 days group, and 77% in the 57-63 days group (p 0.001). Abortion occurred within 4 hours of misoprostol administration in 49% of women and within 24 hours in 75%. Termination rates were higher for women with no previous induced abortions. Side effects such as abdominal pain, nausea, vomiting, diarrhea, and vaginal bleeding were frequent and increased with gestational age. 2% of women with pregnancies of 49 days' gestation or less, compared with 4% in both the 50-56 days and 57-63 days groups, were hospitalized, underwent surgical intervention, and received intravenous fluids. The success rate in this study was lower than that reported by other researchers. This may be related, in part, to the lack of experience with medical abortion in the US.

Publication types

  • Clinical Trial
  • Multicenter Study

MeSH terms

  • Abortifacient Agents, Nonsteroidal* / adverse effects
  • Abortifacient Agents, Steroidal* / adverse effects
  • Abortion, Induced / methods*
  • Adult
  • Drug Therapy, Combination
  • Female
  • Gestational Age
  • Humans
  • Mifepristone* / adverse effects
  • Misoprostol* / adverse effects
  • Pregnancy
  • Pregnancy Trimester, First
  • Receptors, Progesterone / antagonists & inhibitors
  • Treatment Failure
  • United States
  • Uterine Hemorrhage / chemically induced


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