History and efficacy of emergency contraception: beyond Coca-Cola.

Over 30 years of clinical use of emergency contraception has confirmed that such methods substantially reduce the chances of pregnancy, do not entail onerous service provision requirements, and are acceptable to women. The major obstacle to the more widespread use of postcoital methods is a lack of awareness on the part of both potential acceptors and service providers of this important option. Most extensively researched have been the Yuzpe method (200 mcg of ethinyl estradiol and 1.0 mg of levonorgestrel, taken within 72 hours of unprotected intercourse and then 12 hours later), levonorgestrel (two doses of 0.75 mg 12 hours apart starting within 48 hours of unprotected intercourse), and postcoital insertion of a copper IUD. Two new agents--RU-486 and the synthetic progestin and antigonadotropin danazol--offer promise, but require further evaluation. The Yuzpe method is estimated to reduce the likelihood of pregnancy by at least 75%. Lacking in the available literature are studies with rigorous research designs and methodologies capable of generating reliable data on efficacy and side effects, especially among women in developing countries. There is a need, for example, to limit samples to women who have had only one act of unprotected intercourse during a menstrual cycle and to those of proven fertility. Also important are studies that evaluate a range of distributional systems (e.g., vending machines) and user educational approaches. Finally, studies are needed to determine whether the Yuzpe method can be broadened to encompass all the progestins (e.g., desogestrel) used in combined oral contraceptives.