Effects of monophasic low-dose oral contraceptives on fibrin formation and resolution in young women.

OBJECTIVE

The purpose of this study was to examine key variables in the regulation of coagulation and fibrinolysis during intake of low-dose oral contraceptives containing newly developed progestogens.

STUDY DESIGN

Thirty-four healthy young women were allocated to 12 consecutive cycles of treatment with monophasic combinations of 20 micrograms ethinyl estradiol and 150 micrograms desogestrel (n = 15) or 30 micrograms ethinyl estradiol and 75 micrograms gestodene (n = 19). Nonparametric analysis of variance was used for statistical evaluation.

RESULTS

In both groups plasma levels of fibrinogen and Factor VIIc increased, and the capacity of coagulation inhibition was affected by increased protein C and decreased protein S levels. Increased fibrinolytic capacity was indicated by elevated activity and reduced antigen levels of tissue plasminogen activator and by reduced activity and concentration of plasminogen activator inhibitor. Thrombin-antithrombin III complexes and fibrin degradation products were unchanged, signifying no effect of hormonal intake on the degree of activation of the coagulation system or the efficacy of fibrinolysis.

CONCLUSION

The overall dynamic balance between generation and resolution of fibrin was maintained during treatment with both hormonal compounds. Our findings suggest that the risk of thrombosis in normal women should not be increased.