ORAL CONTRACEPTIVE HORMONES AND BLOOD COAGULABILITY.

Abstract

A study was made on the effects of oral contraception on blood coagulability in women being treated with a variety of commercial preparations. The results were compared with those in a group of normal female controls and they were also contrasted with the effects of exercise on coagulability in normal women using the same techniques and with the results in patients with deep-vein thrombosis who presented during the period of the trial. It was found that oral contraceptives caused a rise in factor 7 levels significant from Month 3 onwards. No significant changes in cephalin times or antihemophili antihemophilic globulin (AHG) levels were recorded in the oral contraceptive group unlike the physiological changes found after physical exercise in normal women. Increases in factor 7 levels were detected also in a concurrent study of patients with deep-vein thrombosis but these were also associated with shortened heparin clotting-times not found in the women on oral contraceptives. It is considered that this increase in factor 7 levels which is also found in normal pregnancy and the postpartum state as well as in venous thrombosis is an undesirable side-effect of oral contraception. No woman in the study had been on treatment for more than 2 1/2 years and further study is necessary to determine whether different changes occur at a later date. In future investigations it should be determined whether all the preparations available are equally liable to produce raised factor 7 levels.