A comparative study on the effects of a monophasic pill containing desogestrel plus 20 micrograms ethinylestradiol, a triphasic combination containing levonorgestrel and a monophasic combination containing gestodene on coagulatory factors.

The changes in haemostasis during oral contraception are related to the ethinylestradiol dose present in the formulation taken by the patient. An open, randomized longitudinal study was performed to evaluate and compare the effects that low-dose oral contraceptives (OCs) containing different doses of ethinylestradiol exert on the haemostatic system. Eighty-nine healthy women, aged 18-45 years, were randomly assigned to treatment with 3 different OCs: a monophasic pill containing 30 micrograms of ethinylestradiol plus 75 micrograms of gestodene (GSD/30) (30 subjects), a triphasic pill containing levonorgestrel (TRI/LNG) (28 subjects), a monophasic pill containing 20 micrograms ethinylestradiol plus 150 micrograms of desogestrel (DOG/20) (31 subjects). From every woman, blood samples were collected before treatment and at the 3rd and 6th cycle of pill intake. The number of platelets significantly increased (p less than 0.01) during treatment with TRI/LNG. Fibrinogen plasma values were significantly increased (p less than 0.05) only in women treated with the preparation GSD/30. Fibrinopeptide A (FPA) plasma levels significantly increased (p less than 0.01) during treatment with the pills TRI/LNG and GSD/30, but the levels of FPA were unchanged in the group treated with DOG/20. The overall results of this study confirm that the effects of OCs on haemostasis are dependent on the ethinylestradiol dose. Moreover, they suggest that with reduction of the ethinylestradiol component to 20 micrograms, the effects of OCs on haemostasis seem to be virtually eliminated.