Clinical experience with a low-dose contraceptive agent. European studies.

After widespread publicity about major adverse reactions to oral contraceptive agents, combinations were tested that contained lower doses of sex steroids than had been used before. Among them, the combination of levonorgestrel, 150 micrograms, and ethinyl estradiol, 30 micrograms, was studied intensively. European studies exclusive of the British Isles were conducted on 3,733 patients through approximately 36,000 cycles. There were nine pregnancies, for a Pearl index of 0.3. Cycle regulation was excellent, with normalization of menstrual flow. Amenorrhea was reported in 2.3% or less of cycles. No serious side effects were reported. The decrease in estrogen dosage, usually accompanied by a decrease in the progestational component, has resulted in a decrease in reported thromboembolic disease. Factors still important are diabetes mellitus, hypertension, obesity and cigarette smoking.