Effects of two oral contraceptives, containing 30 or 20 microg of ethinyl estradiol in combination with gestodene, on blood coagulation and fibrinolysis in Brazilian women.

OBJECTIVE

Blood coagulation and fibrinolytic variables were evaluated in 46 Brazilian women treated with either of two monophasic oral contraceptives (OC), containing 30 or 20 microg of ethinyl estradiol, and 75 microg of gestodene.

METHODS

The effects on procoagulants, anticoagulants, pro-fibrinolytics and antifibrinolytics and fibrin turnover were evaluated after treatment for six consecutive cycles, the impact of reduction of ethinyl estradiol dosage on these effects being assessed.

RESULTS

The OC containing 30 microg of ethinyl estradiol significantly increased the activities of factors VIII and X, whereas the one containing 20 microg of ethinyl estradiol caused no changes in clotting factors. Neither treatment altered fibrinogen levels or factor VII, IX or XII activity. There were no changes in antithrombin levels, but treatment with 30 microg ethinyl estradiol increased protein C levels and treatment with 20 microg decreased total protein S levels. Concerning the fibrinolytic parameters, both OCs increased plasminogen activity, whereas no changes in PAI-1, t-PA, alpha-2-antiplasmin or fibrin degradation products were observed. The reduction in ethinyl estradiol dosage from 30 microg to 20 microg eliminated the effects on factors VIII and X.

CONCLUSIONS

The results show that the OC studied did not cause sufficient changes to indicate that there may be a correlation between these laboratory alterations and clinical results. The lack of reports concerning the hemostatic effects of OCs on Brazilian women hinders comparison of the present data with those obtained for other ethnic groups, at different geographical locations, and emphasizes the importance of such a study for future epidemiological investigation of the prothrombotic effects of OCs in Brazilian women.