Plasma antithrombin III levels in pre-eclampsia.

In a prospective study plasma AT III was determined in 2423 samples obtained from 653 women during pregnancy and post partum. The women were allocated to groups, according to the highest diastolic blood pressure, in the third trimester. AT III levels were normal throughout pregnancy, during labour and after vaginal delivery, except in 57 women with pregnancy induced or aggravated hypertension. We present evidence that AT III depression in pre-eclampsia is caused by increased consumption. AT III levels correlate with maternal morbidity as revealed by hepatorenal damage. A weak but significant correlation of AT III and platelets with placental infarction was demonstrated. Proteinuria was the best predictor of fetal outcome. AT III plasma levels increased the number of correct predictions. Following vaginal delivery AT III plasma levels rapidly returned to normal values.