Low-dose combination oral contraceptives: a controlled clinical study of three different norgestrel-ethinyl estradiol ratios.

Three doses of norgestrel-ethinyl estradiol in altered ratios were investigated in a double-blind, randomized study. The estrogen content was maintained at 20 microng or less, while the progestogen dose was increased in 100-microng increments. Two pregnancies were reported for the lowest dose. No pregnancies occurred in the two higher doses. Each dosage increase improved cycle control and lessened bleeding irregularities. The incidence of patients reporting intermenstrual bleeding was inversely proportional to the doses studied. Dropouts for cycle disturbances followed a similar pattern.