Emergency Contraception.

Emergency contraception (EC) may help prevent pregnancy in various circumstances, such as contraceptive method failure, unprotected sexual intercourse, or sexual assault, yet it remains underused. There are 4 approved EC options in the United States. Although ulipristal acetate requires a provider's prescription, oral levonorgestrel (LNG) is available over the counter for women of all ages. The most effective method of EC is the copper intrauterine device, which can be left in place for up to 10 years for efficacious, cost-effective, hormone-free, and convenient long-term primary contraception. Ulipristal acetate tends to be more efficacious in pregnancy prevention than is LNG, especially when taken later than 72 hours postcoitus. The mechanism of action of oral EC is delay of ovulation, and current evidence reveals that it is ineffective postovulation. Women who weigh more than 75 kg or have a body mass index greater than 25 kg/m(2) may have a higher risk of unintended pregnancy when using oral LNG EC; therefore, ulipristal acetate or copper intrauterine devices are preferable in this setting. Providers are often unaware of the range of EC options or are unsure of how to counsel patients regarding the access and use of EC. This article critically reviews current EC literature, summarizes recommendations, and provides guidance for counseling women about EC. Useful tips for health care providers are provided, with a focus on special populations, including breast-feeding women and those transitioning to long-term contraception after EC use. When treating women of reproductive age, clinicians should be prepared to counsel them about EC options, provide EC appropriately, and, if needed, refer for EC in a timely manner.