Postcoital contraception with dl-norgestrel/ethinyl estradiol combination: six years experience in a student medical clinic.

Postcoital contraception with ethinyl estradiol/dl-norgestrel in combination has been available to women students attending the University of British Columbia since 1974. This paper reports on the side effects, cycle control and efficacy, for a six-year period (1979-1985). In this sample of women 50% reported side effects of nausea alone or nausea with vomiting. Length of the menstrual cycle was shortened in women who took the medication prior to the expected day of ovulation. The number of pregnancies reported was significantly (p less than 0.002) less than the number expected had the medication not been taken. Some women took the medication even though there was a possibility of conception earlier in the cycle and this might account for four of the failures. The mode of action of the postcoital medication remains unsolved making it difficult to understand possible reasons for the other 14 failures.