The Morning After Pill

Emergency contraception is any kind of birth control that is used after sex, but before implantation of the embryo into the uterus. Emergency contraceptive pills (ECPs) are marketed in the US under the name “Plan B.” ECPs consist of the same synthetic hormones found in oral contraceptives. They are taken within 72 hours of unprotected intercourse by women who do not want to become pregnant.

How ECPs work

The emergency contraceptive/morning after pill has three possible ways in which it can work:

1. Ovulation is inhibited, meaning the egg will not be released.
2. The normal menstrual cycle is altered, delaying ovulation.
3. It can alter the lining of the uterus so that if the 1st and 2nd actions fail, and the woman does become pregnant, the tiny baby girl or boy will die before he/she can actually attach to the lining of the uterus.

Effectivness of emergency contraceptive pills

After a single act of intercourse, on average the pregnancy rate would be 8% with no contraception. In clinical trials, the risk of pregnancy was reduced to 1%. Thus, Plan B reduced the expected number of pregnancies by 89%. However, it should be noted that the effectiveness found in real-life is never quite as good as in clinical trials, so the effectiveness could be somewhat less. Also the drug is less effective if taken more than 72 hours later.

Side-effects and health risks of ECPs

The most common side-effects in the clinical trials for women receiving Plan B included nausea (23%), abdominal pain (18%), fatigue (17%), headache (17%), dizziness (11%), menstrual changes (26%), breast tenderness (11%), vomiting (5.6%), and diarrhea (5%).