Dear Casperx2,

Emergency contraception (EC) — also known as the "morning-after pill" — is one of the safest and most effective ways to prevent unintended pregnancy after unprotected sex or contraceptive failure.

EC does not cause an abortion — instead, EC helps prevent pregnancy. The hormones in EC work by keeping a woman's ovaries from releasing eggs. Pregnancy cannot happen if there is no egg to join with sperm. The hormones also prevent pregnancy by thickening a woman's cervical mucus. The mucus blocks sperm and keeps it from joining with an egg.

Some people say that EC works by keeping a fertilized egg from attaching to the lining of the uterus. But scientists say that this does not happen.

EC reduces the risk of pregnancy when started within 120 hours (five days) of unprotected sex. If started within 72 hours, it can reduce the risk of pregnancy by 75-89 percent. The sooner it's started, the better.

Plan B, a brand of EC, is available over the counter at many pharmacies for women over 17. Teens under 17 can still access EC with a prescription. EC is available at Planned Parenthood health centers, as well as college, public, and women's health centers.

Many Planned Parenthood health centers have weekend and evening hours to help women get the services they need, when they need them — fast. However, the best way young women can protect themselves is to get EC before an accident happens and keep it on hand in case they need it. That way, they won't waste time after unprotected intercourse waiting to get an appointment with a health care provider and trying to get a prescription filled.