Of the estimated 3.5 million unintended pregnancies that occur each year in the United States, some 1.7 million are thought to be the result of contraceptive failure. The extremely high numbers of unintended pregnancies not only in the United States but also worldwide indicates that emergency contraception remains an important but underused method of pregnancy prevention. Emergency postcoital contraception via mechanical or pharmacological means inhibits fertilization and/or implantation from unprotected sexual intercourse. Although emergency contraception has been used primarily in victims of sexual assault, it offers a low-cost, highly effective n1ethod to reduce the incidence of unintended pregnancy.

Emergency contraception decreases the costs and emotional and physical risks to women who have had unprotected intercourse. Emergency contraception also increases the latitude women have to make reproductive decisions by offering an alternative to abortion and childbearing. The heart of the problem with emergency contraception is not the failure rate or side effects of specific methods but the fact that so few women and adolescents who have had unprotected intercourse know the option exists, and their providers may be reluctant to prescribe the method.