Thrombin-antithrombin III complex levels in normal pregnancy with hypertensive disorders and after delivery

The plasma concentration of the thrombin-antithrombin III-complex (TAT) was investigated during uncomplicated pregnancy in 15 women in the first, 22 in the second and 46 in the third trimester, and in 19 women with hypertensive disorders between 25 and 40 weeks gestation. Eight women at term after a normal pregnancy were studied before the onset of labour and within 60 min and 24 h after delivery. A comparison group of 16 healthy, non-pregnant women was investigated. The mean TAT concentration in normal pregnancies increased significantly in the second and third trimester compared with values in the first trimester and in non-pregnant women. In the group with hypertensive disorders during pregnancy TAT levels were significantly higher than in uncomplicated pregnancies. Within 60 min after delivery a distinct increase of TAT concentrations occurred compared to levels before the onset of labour but the levels had returned to normal by 24 h after delivery. Our findings suggest that an activation of the coagulation system occurs in normal pregnancy. A further activation takes place immediately after delivery. The significantly increased TAT levels in pregnancies with hypertensive disorders suggest a state of chronic disseminated intravascular coagulation leading to an enhanced consumption of and a decreased plasma concentration of antithrombin III.