ABSTRACT
This chapter evaluates the effects of two oral contraceptives (OCs) with equal dose of ethinylestradiol, but with a different type and dose of progestogen on variables of coagulation and fibrinolysis which are recognized as risk indicators for arterial or venous disease. Both coagulation and fibrinolytic factors are important for arterial and venous thromboembolic disease. Sex hormones affect both coronary heart disease and thrombogenesis, including factors involved in the hemostatic balance. Lowering of the estrogen dosage in OC preparations was associated with a decrease in the incidence of venous thrombo-embolic events and the observation of the increased cardiovascular mortality could not be reproduced. As found elsewhere during the administration of OCs nearly all arterial and venous risk factors changed; the mean values of coagulatory and fibrinolytic factors seemed to change in opposite directions, suggesting maintenance of the hemostatic balance, but in individual cases this may often be different.
