Enhanced generation and resolution of fibrin in women above the age of 30 years using oral contraceptives low in estrogen.

Epidemiologic studies have suggested a relationship between the use of oral contraceptives and mortality from cardiovascular diseases in older women. Therefore we studied generation and resolution of fibrin in 28 healthy women above age 30 years, using oral contraceptives containing 30 to 50 micrograms of ethinyl estradiol. Thirty healthy nonusers served as control subjects. The oral contraceptive group had increased plasma concentration of thrombin-antithrombin III complexes (p less than 0.01), which indicated an enhanced generation of thrombin, increased plasma activity of tissue-type plasminogen activator (p less than 0.01), decreased plasma activity of plasminogen activator inhibition (p less than 0.01), and increased plasma concentration of fibrin degradation products (p less than 0.04). Interestingly, the ratio of thrombin-antithrombin III complexes/fibrin degradation products did not deviate significantly between groups. Twelve of the 28 women using oral contraceptives were light smokers, that is, less than 15 cigarettes per day. There were no differences in the determined variables between smokers and nonsmokers. Our study suggests that healthy women older than 30 years who use oral contraceptives containing 30 to 50 micrograms of ethinyl estradiol have an enhanced generation and resolution of fibrin, while the hemostatic balance is unaltered. These findings are unaffected by moderate cigarette smoking.