Effect of oral contraceptives and ovarian cycle on platelet function.

In past decades, numerous epidemiological and clinical studies in women taking oral contraceptives revealed the impact of sex steroids on coagulation factors and the incidence of venous thrombosis. To date, only scarce data regarding the impact of oral contraceptives on platelet function are available. The aim of this study was to further elucidate the impact of sex steroids on platelet function. We conducted an observational study in young women using different types and dosages of monophasic oral contraceptives (OCs) compared to women not taking OCs. During the follicular phase, the mean closure time (CT) in Col/Epi was 168.0 +/- 64.9 s compared to 131.5 +/- 28.9 s during the luteal phase (p=0.012). In Col/Epi cartridges, no difference was detected between women taking second/third generation OCs and low-dose OCs (145.2 +/- 44.3 vs. 169.4 +/- 63.5, p=0.34). In contrast, mean Col/Epi values of women using anti-androgen-containing OCs were less (110.3 +/- 15.6 s) than in both other OC groups (p=0.03 for both comparisons). The same holds for Col/Epi values from women during the follicular- and luteal phases compared to women using anti-androgen-containing OCs (p=0.0002, p=0.013). Significant correlations between progesterone and platelet function in women not using OCs (p=0.02) could be found. In conclusion, the results of the study show that platelet function might be modulated by OCs and the female cycle. As for OCs, the main factor seems to be the progestagen. During the female cycle, the main impact on platelet function might be mediated by progesterone.