Effects of two triphasic oral contraceptives containing ethinylestradiol plus levonorgestrel or gestodene on blood coagulation and fibrinolysis.

The hemostatic effects of a new triphasic oral contraceptive combination containing ethinylestradiol and the new progestogen gestodene were compared with those of a triphasic combination of ethinylestradiol and levonorgestrel. A total of 19 women who did not use any kind of hormonal contraception 3 months prior to the study were recorded. The following parameters were measured: whole blood clotting time (WBCT), whole blood clot lysis time, fibrinogen, antithrombin III, factors V, VII and VIII. Blood samples were taken before treatment and in cycles 1, 3 and 6. A significant shortening of WBCT was observed in cycle 3 and 6 in both groups and also in cycle 1 in the gestodene group. This may indicate an increased sensitivity for activation of platelets, since the assay appears to be quite sensitive to this process. In the other parameters tested there were no significant changes except for a slight increase in plasma fibrinogen in cycle 1 in the gestodene group.