Thrombin-antithrombin complex and alpha-plasmin inhibitor-plasmin complex levels in singleton and twin pregnancies

Thrombin-antithrombin complex (TAT) is a sensitive marker for thrombin formation, and alpha2-plasmin inhibitor-plasmin complex (PIC) is a marker for fibrinolysis. Previous studies have shown that blood coagulation and fibrinolysis are activated in normal pregnancies. Thus, the present study examined changes in TAT and PIC levels during the course of singleton and twin pregnancies and compared these markers between the two pregnant groups. The subjects were 148 pregnant women, of whom 84 were women carrying single fetuses and 64 were women with twin fetuses. Their average gestational age at entry was 10, 20, 30 and 38 weeks of gestation in singleton pregnancies and 10, 20, 30 and 35 weeks in twin pregnancies. Peripheral blood was collected, and plasma was separated after centrifugation and then stored at -20 degrees C. The TAT levels increased significantly with the progression of pregnancy in both pregnant groups, whereas the PIC levels increased significantly only in singleton pregnancies between 30 and 38 weeks of gestation. The TAT levels were significantly higher in twin pregnancies than in singleton pregnancies. The PIC levels were significantly lower in twin pregnancies than in singleton pregnancies at 35-38 weeks. Thrombin formation might be enhanced with the progression of pregnancy in both pregnant groups. This enhancement might be more intensified in twin pregnancies. Fibrinolysis might increase only in singleton pregnancies from 30 to 38 weeks of gestation. Fibrinolysis might be less intensified in twin pregnancies than in singleton pregnancies only at 35-38 weeks.