Postcoital contraception.

The evolution of postcoital contraception has led to the development of emergency measures to be used following a single unprotected act of intercourse and to ongoing methods, such as the administration of a contraceptive steroid agent following every coital exposure. In emergency situations, the most commonly employed hormonal steroids are the synthetic, conjugated and natural estrogens, administered in large doses for five days. Recently, a combination of an estrogen and a progestin has been employed for the same purpose. A copper-bearing intrauterine device (IUD), inserted within seven days of coitus, has also been utilized with success. Progestins alone have been utilized as an ongoing method of postcoital contraception. Failure rates have been found to vary with the dosage, the specific progestin employed and the frequency of intercourse. The major role of postcoital contraception in the developed world appears to be as an emergency measure. Ease of availability, a high degree of efficacy and a low incidence of side effects are essential for patient and physician acceptance.