A new postcoital oral contraceptive

Abstract

Large doses of estrogens have been used by several investigators as "emergency" postcoital contraceptives but their true effectiveness in the human is not known. We report here the results of the use of quingestanol acetate, a progestagen, taken routinely by fertile, married women in a single dose less than 24 hours after coitus. Two-hundred and twenty-one patients were studied for 927 menstrual cycles using a dose of 0.5 mg and 200 patients for 1004 cycles using 0.8 mg; with doses of less than 0.5 mg there was little or no contraceptive effect, 0.5 mg was a fairly good contraceptive, and with 0.8 mg no pregnancies resulted. An average of eleven doses was taken per menstrual cycle; the only important adverse effect was breakthrough bleeding. Studies are continuing with these and other doses. © 1970.