The Difference Between Medical Abortion and Emergency Contraceptive Pills
(Updated December 2010)
There is considerable confusion, even among experienced health care providers, about the difference between medical abortion (also known as “medication abortion”) and emergency contraceptive pills (also known as “morning-after pills”). Emergency contraceptive pills help prevent pregnancy; medical abortion terminates an established pregnancy.
According to the best scientific evidence available, all FDA-approved emergency contraceptive pills work by interfering with ovulation or fertilization before pregnancy begins and are not so-called “abortion pills.” ARHP, the American College of Obstetricians and Gynecologists1, and the US Department of Health and Human Services2 endorse the general medical definition of pregnancy as beginning when a pre-embryo completes implantation into the lining of the uterus.
Emergency contraceptive pills help prevent pregnancy.
Medical abortion (medication abortion) terminates an established pregnancy.
What is medical abortion?
Medical abortion is the use of medications that can induce abortion. Currently three treatment regimens are available in the United States for this purpose: mifepristone combined with misoprostol, methotrexate combined with misoprostol, and misoprostol by itself.3,4 Regimens that contain mifepristone and misoprostol are more commonly used because they are more effective and predictable.5,6 Mifepristone is also known as RU-486 or Mifeprex®. In the small percentage of cases in which medical abortions fail, surgical abortion procedures are required to end the pregnancy.
What are emergency contraceptive pills (ECPs)?
Women may use ECPs as a means of preventing pregnancy after unprotected intercourse. ECPs are especially useful in cases of unanticipated sexual activity, contraceptive failure, or sexual assault. ECPs contain hormones that reduce the risk of pregnancy if taken within 120 hours (5 days) of unprotected intercourse. Plan B®, Next Choice™, Levonorgestrel, and ella® are currently the only products marketed specifically as emergency contraceptive pills in the United States. Certain oral contraceptives taken in increased doses also may be used as ECPs. Mifepristone has also been shown to be effective for emergency contraception, but is not approved for this use in the United States.
Plan B® One Step
The FDA-approved regimen of mifepristone is 600 mg orally followed 2 days later by misoprostol 400 µg orally for women up to 49 days' gestation. A small percentage (2% to 5%) of women may abort before taking misoprostol,7,8,9 so it is reasonable to administer Rh immune globulin to appropriate patients at the time of the first visit. Evidence supports the safety and efficacy for women up to 63 days' gestation with use of vaginal misoprostol.10 For women beyond 49 days' gestation, the use of vaginal, rather than oral, misoprostol increases the efficacy of medical abortion.11
ECPs are effective up to 120 hours after intercourse.12Treatment with Plan B One Step and Next Choice, or Levonorgestrel should be initiated as soon as possible after intercourse, because efficacy declines substantially with time .13,14While the effectiveness of progestin-only pills declines with delay in treatment, the effectiveness of ella does not (up to 120 hours).
Levonorgestrel-only regimen: 1.50 mg levonorgestrel in a single dose or in two doses of 0.75 mg taken up to 12 hours apart.
Ulipristal acetate regimen: 30 mg ulipristal acetate in a single dose.
Combined estrogen-progestin (Yuzpe) regimen: two doses of 100 mcg ethinyl estradiol plus 0.50 mg of levonorgestrel taken 12 hours apart.
|Mechanism of Action
||Mifepristone ends pregnancy by blocking the hormones necessary for maintaining a pregnancy. Methotrexate is a folic acid antagonist and damages the rapid growth of the chorionic villi, which, in turn, effectively dislodges the pregnancy from the uterus. Misoprostol causes the uterus to contract and empty.
||Depending on the time during the menstrual cycle that they are taken, ECPs may inhibit or delay ovulation, inhibit tubal transport of the egg or sperm, interfere with fertilization, or alter the lining of the uterus inhibiting implantation of a fertilized egg.|
Millions of women around the world have used medical abortion safely.3
Among the estimated 850,000 US women who have used mifepristone for early abortion, seven deaths have occurred - six from rare infections associated with childbirth and abortion and one from a ruptured ectopic pregnancy. Six infection-related deaths have been reported to the US Food and Drug Administration; the death rate is comparable to that of surgical abortion and miscarriage and lower than the death rate from a delivery. It is not known whether using Mifeprex® and misoprostol caused these deaths.15
Millions of women around the world have used ECPs safely.16,17
There are no evidence-based contraindications for ECPs.
ECPs will not induce an abortion in a woman who is already pregnant, nor will they affect the developing pre-embryo or embryo.18
Medical abortion regimens are highly effective at ending very early pregnancies.
Complete abortion will occur in 92-96% of women who receive the methotrexate regimen. Complete abortion will occur in 96- 97% of women who receive the mifepristone regimen.4
ECPs can reduce the risk of pregnancy by between 75 and 99 percent.
ECPs reduce the risk of pregnancy when taken up to 120 hours after unprotected intercourse.
||Most common side effects are similar to those of a spontaneous miscarriage (abdominal pain, bleeding, and gastrointestinal distress).19,20
Most common side effects include nausea and vomiting.
Breast tenderness, fatigue, irregular bleeding, abdominal pain, headaches, and dizziness may occur.
||In the United States, the price of medical abortion ranges between $350 and $575, which may include two or three office visits, testing, and exams.
||In the United States, the price of ECPs ranges from $10 to $77 per use.|
- American College of Obstetricians and Gynecologists. Statement on Contraceptive Methods. Washington, DC: ACOG; 1998.
- US Department of Health and Human Services. Code of Federal Regulations. 45CFR46.203. 1978.
- Creinin MD, Aubény E. Medical abortion in early pregnancy. In Paul M, Stubblefield PG, Grimes DA, et al, eds. A Clinician’s Guide to Medical and Surgical Abortion. New York: Churchill Livingstone; 1999.
- Schaff EA, Fielding SL, Eisinger SH, et al. Low-dose mifepristone followed by vaginal misoprostol at 48 hours for abortion up to 63 days. Contraception 2000;61(1):41-46.
- Grimes DA, Creinin MC. Induced abortion: an overview for internists. Ann Intern Med 2004;140(8):620-626.
- Wiebe ER, Dunn S, Guilbert E, et al. Comparison of abortions induced by methotrexate or mifepristone followed by misoprostol. Obstet Gynecol 2002;99(5):813-819.
- Peyron R, Aubény E, Targosz V, et al. Early termination of pregnancy with mifepristone (RU 486) and the orally active prostaglandin misoprostol. N Engl J Med 1993;328:1509-1513.
- Spitz IM, Bardin CW, Benton L, Robbins A. Early pregnancy termination with mifepristone and misoprostol in the United States. N Engl J Med 1998;338:1241-1247.
- Aubény E, Peyron R, Turpin CL, et al. Termination of early pregnancy (up to 63 days of amenorrhea) with mifepristone and increasing doses of misoprostol. Int J Fertil Menopausal Stud 1995;40(suppl):85-91.
- Kahn JG, Becker BJ, MacIsaac L, et al. The efficacy of medical abortion: a meta-analysis. Contraception 2000;61:29-40.
- el-Refaey H, Rajasekar D, Abdalia M, et al. Induction of abortion with mifepristone and oral or vaginal misoprostol. N Engl J Med 1995;332:983-987.
- Ellertson C, Evans M, Ferden S, et al. Extending the time limit for starting the Yuzpe regimen of emergency contraception up to 120 hours. Obstet Gynecol 2003;101:1168-71.
- Piaggio G, von Hertzen H, Grimes DA, et al. Timing of emergency contraception with levonorgestrel or the Yuzpe regimen. Task Force on Postovulatory Methods of Fertility Regulation (letter). Lancet 1999;353:721.
- von Hertzen H, Piaggio G, Ding J, et al. Low dose mifepristone and two regimens of levonorgestrel for emergency contraception: a WHO multicentre randomized trial. Lancet 2002;360:1803-10.
- U.S. Food and Drug Administration. Questions and Answers on Mifeprex (mifepristone). August 2007.
- Guillebaud J. Time for emergency contraception with levonorgestrel alone. Lancet 1998 Aug 8;352(9126):416-7. Erratum in: Lancet 1998 Aug 22;352(9128):658.
- Van Look PF. Emergency contraception: a brighter future? Entre Nous Cph Den 1998 Autumn;(39):4-5.
- Bacic M, Wesselius de Casparis A, Diczfalusy E. Failure of large doses of ethinyl estradiol to interfere with early embryonic development in the human species. Am J Obstet Gynecol 1970;107:531-4.
- Creinin MD, Fox MC, Teal S, et al. A randomized comparison of misoprostol 6 to 8 hours versus 24 hours after mifepristone for abortion. Obstet Gynecol 2004; 103: 850-9.
- Schaff EA, Fielding SL, Westhoff C, et al. Vaginal misoprostol administered 1, 2, or 3 days after mifepristone for early medical abortion: a randomized trial. JAMA 2000;284:1948-1953.