Emergency contraception is a way to prevent pregnancy after unprotected sex. Often called the morning-after pill, emergency contraceptive pills (ECPs) are pills that can be taken up to 120 hours (5 days) after having unprotected sex. Some types of emergency contraception work best when taken within 72 hours (3 days) after intercourse.
The IUD can sometimes be used as a form of emergency contraception.
How Does Emergency Contraception Work?
Emergency contraceptive pills work by delaying ovulation (the release of an egg during the monthly cycle). If fertilization and implantation have already happened, ECPs will not interrupt the pregnancy.
How Well Does Emergency Contraception Work?
About 1 or 2 in every 100 women who use ECPs will become pregnant despite taking the pills within 72 hours after having unprotected sex.
The "morning-after" name is somewhat misleading: You don't have to wait until the next morning to take ECPs. Emergency contraception is most effective when taken as soon as possible after unprotected sex.
Emergency contraception will not prevent pregnancy if unprotected sex happens after taking the ECPs.
Emergency contraception does not prevent all pregnancies. So a girl should see a doctor if she doesn't get her next expected period after taking ECPs.