Generation of thrombin in blood plasma of non-pregnant and pregnant women studied through concentration of thrombin-antithrombin III complexes

Objective: The main question in this study is how much more thrombin is generated in blood plasma of pregnant women than in non-pregnant women. Study design: Thrombin-antithrombin III complexes (TAT) were used as markers of thrombin generation in vivo. They were measured by the ELISA method in blood plasma of 15 non-pregnant and 43 pregnant, as well as 30 parturient women and 10 women after delivery. Results: With normal menstrual cycles, TAT levels did not change significantly throughout the cyclic phases, and the mean+/-S.D. calculated for all cyclic phases was 1.9+/-0.3 mu g/l. In the 2nd trimester the level of TAT was 16.0+/-2.8 mu g/l and at term 21.5+/-11.9 mu g/l. Throughout the 1st and 2nd stage of labour the level of TAT increased insignificantly, but after placenta separation it was significantly higher than before labour (30.8+/-20.4 mu g/l). In the 3rd and 7th days after delivery the level of TAT was still higher than in non-pregnant women. Conclusion: It was found that the level of TAT in normal menstrual cycles is stable, whereas it increases in pregnancy. Relating the values of the cycle to those of pregnancy it was calculated, that at the end of pregnancy there is a ten-fold increase of TAT level and after placenta separation and expulsion - temporarily even fifteen-fold - increase. In the 3rd to 7th day after delivery, the TAT level was still higher than in non-pregnant women. (C) 1997 Elsevier Science Ireland Ltd.