If you have sex and have forgotten to use your birth control, you can either take emergency oral contraceptives or have a copper IUD placed by your healthcare provider. Both oral and intrauterine emergency contraceptives are only effective before a pregnancy has implanted. When used within 72 hours of unprotected intercourse, the copper IUD prevents 95% of expected pregnancies, ulipristal acetate (an antiprogestin; Brand name: Ella; prescription-only) prevents ⅔ of expected pregnancies, and levonorgestrel (a progestin; Brand names: Plan B One-Step, Next Step One Dose, Take Action; available over-the-counter) prevents 50% of expected pregnancies.
