Emergency contraception (EC) is widely used to prevent unwanted pregnancy. This review considers the safety and efficacy of three commonly used methods -- levonorgestrel (LNG-EC), ulipristal acetate (UPA) and the copper intrauterine device. All are extremely safe, and side effects are minimal. Concerns about increased risks of ectopic pregnancy after EC use have proved unfounded, and possible teratogenic effects seem unlikely. Although the true effectiveness of EC is impossible to estimate, recent research suggests that LNG-EC prevents around 50% of expected pregnancies in women using the method within 72 h of intercourse, whereas UPA appeared to prevent almost two thirds of pregnancies. Emergency intrauterine device insertion probably prevents over 95% of pregnancies. However, although improved accessibility of EC has clearly led to increased use, it does not appear to have had any public health benefit in reducing unintended pregnancy rates. Most of the data on sexual behavior following improved access to EC do not show any detrimental effect on subsequent use of other more effective methods of contraception or on the incidence of unintended pregnancy or sexually transmitted infection. However, unless these other methods of contraception are also made easily available from pharmacies, improved access to EC risks unlinking its use with use of subsequent ongoing contraception.
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