A multicenter clinical investigation employing ethinyl estradiol combined with dl-norgestrel as postcoital contraceptive agent.

Six hundred ninety-two women were enrolled in a multicenter clinical trial to evaluate a combination of ethinyl estradiol and dl-norgestrel as a postcoital contraceptive. When compared with various formulas predicting the probability of pregnancy in this group, the number of pregnancies observed appears to be reduced by approximately 84%. The combination of 200 micrograms of ethinyl estradiol and 2 mg of dl-norgestrel seems to be effective as a postcoital contraceptive with several advantages over estrogens alone.