Birth Control Options for Women - Emergency Contraception

Specific Methods

Emergency Oral Contraception. There are two forms of emergency oral contraception:

The Yuzpe method is the most common method. It simply employs two doses of combined oral contraceptives containing estrogen and the progestin levonorgestrel. (Some evidence suggests that combinations with other progestins, such as norethindrone, may also be useful). In general, this approach is effective in preventing pregnancies 75% of the time (although some studies report lower success rates).
The other standard approach uses two doses of the progestin levonorgestrel, which includes Plan B (approved in the US), Ovrette, and Levonelle (in the UK). Studies indicate that this method causes less stomach distress and is more effective than the Yuzpe method. In one large study, levonorgestrel prevented pregnancy in 85% of women requiring emergency contraception.

With both methods, the woman takes her first pill or pills within 72 hours of intercourse and a second dose 12 hours later. The earlier they are taken, the more effective they are in preventing pregnancy. Some evidence suggests they may be effective up to five days after sex, although effectiveness is greater if used within 72 hours. Although these regimens are popularly called morning-after pills, they are actually the same oral contraceptives that users of OCs take regularly.

Side effects of emergency oral contraception methods include:

Nausea and vomiting are common in both approaches, but particularly with the Yuzpe method.
Fatigue.
Headaches.
Dizziness.
Diarrhea.
Breast tenderness.
Fluid retention.
Changes in the timing or flow of the woman's next menstrual period.

Immediate side effects typically subside within a day or two of taking the second dose. Family planning experts warn that emergency pill use should not be treated as a substitute for regular contraception.

Copper-Releasing IUD. An alternative emergency contraception relies on insertion of a copper-releasing IUD within five days of intercourse. It can be removed after the woman's next period, or left in place to provide ongoing contraception. The copper IUD reduces the risk of pregnancy by 99.9%.

Mifepristone. Mifepristone, also called RU486, Mifeprex, and the "abortion pill," blocks progesterone action so that the lining thins and deters implantation of the egg. Unlike emergency oral contraception, this agent can abort an existing pregnancy. A single dose used within 72 hours of unprotected sex can prevent pregnancy. Some researchers believe mifepristone may have the potential to be given in low-doses for on-going contraception, much like the combined pill.

When used after pregnancy occurs, mifepristone is taken within forty-nine days of a woman's last period. The woman is given three pills by her doctor during her first visit, and then a second drug (misoprostol) two days later. The second drug, misoprostol, causes uterine contractions that will expel the embryo. A third visit is needed to ensure the abortion is successful. Women who have ectopic or tubal pregnancies cannot take mifepristone. Side effects include pain, and use of the pills may also cause nausea and bleeding. In four out of 2,100 American women tested, bleeding was heavy enough to require transfusion.