Blood coagulation in pregnancy induced hypertension.

Decreased plasma levels of antithrombin III (AT III) are observed in women with severe pregnancy-induced or aggravated hypertension. Low AT III levels correlate with the platelet count and with symptoms of maternal and foetal morbidity. Therefore, in clinical practice both the platelet count and the plasma AT III levels provide significant information regarding the clotting disturbances in toxemic patients. Established AT III deficiency may explain the enhanced post-partum thrombosis risk in these patients. Primary prophylaxis in patients undergoing caesarean section with oral anticoagulants is preferred because of an observed enhanced bleeding tendency upon heparin prophylaxis.