OBSTETRICS AND GYNAECOLOGY

Retrospective statistical epidemiological studies have suggested a possible association between the ingestion of oral contraceptives (OC) and thromboembolic disease. Past analyses of the coagulation system have yielded controversial information. We studied a cross section of 131 women taking different kinds of OC and 36 controls for changes in hemostasis. No significant differences were noted in the levels of fibrinopeptide A (RIA), platelet factor 4, 8 thromboglobulin (RIA), fibrinogen (Multistat III (MCA), clot table), antithrombin III (MCA, S-2238), a2 antiplasmin (MCA, S-2251), prekallikrein (MCA, S-2302) and fibronectin (MCA, immune turbidometric). However, plasminogen (MCA, S-2251) and protein C antigen (Laurel!) levels were significantly elevated (p < 0.001 and p < 0.01), respectively). Canonical correlation analysis was used to examine correlations between hemostasis parameters measured and clinical risk factors, such as age, parity, weight, smoking, family history for thromboembolic diseases and estrogen-progesterone dose. There was a significantly negative correlation between family history for thromboembolisms and antithrombin III levels (p < 0.01). A positive correlation existed between obesity and fibrinogen and fibronectin levels (p < 0.001 for both). The hemostasis data seem to suggest that OC use does not introduce an imbalance in the hemostasis system which fosters "hypercoagulability", and that, if at all, possibly other risk factors determine the incidence of thromboembolisms in OC users. It is suggested that caution be exercised in the use of OCs in patients with a history of thromboembolic diseases and with obesity.