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Emergency contraception

Andrew M Kaunitz, MD
Section Editor
Courtney A Schreiber, MD, MPH
Deputy Editor
Kristen Eckler, MD, FACOG


Emergency contraception (also known as postcoital contraception and the morning-after pill) refers to the use of drugs or a device as an emergency measure to prevent pregnancy. Women who have had recent unprotected intercourse, including those who have had a failure of another method of contraception, are potential candidates for this intervention. It is intended for occasional or back-up use, not as a primary contraceptive method for routine use. (See "Contraceptive counseling and selection".)

Health professionals should inform women about use of emergency contraception and the available options. This discussion should include the advantages and disadvantages of each method, including efficacy and side effects. Males should also be aware of emergency contraception as a method of preventing pregnancy in their partners. In the United States, one in nine reproductive aged women used emergency contraception at least once between 2006 and 2010 [1].


As discussed above, candidates for emergency contraception are women who have had recent unprotected intercourse (including sexual assault), or who have had a recent possible failure of another method of contraception, and who do not desire pregnancy. A detailed list of potential indications is shown in the table (table 1).


Direct laboratory evidence overwhelmingly supports the hypothesis that oral emergency contraceptives work primarily by delaying ovulation [2-6]. Copper intrauterine contraception inhibits fertilization by affecting sperm viability and function [7]. The copper device also has postfertilization contraceptive effects [8]. (See "Intrauterine contraception: Devices, candidates, and selection".)

Both oral and intrauterine emergency contraceptives are only effective before a pregnancy has implanted [9]. These treatments are ineffective once implantation has occurred.

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Literature review current through: Nov 2017. | This topic last updated: Aug 16, 2017.
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