We measured thrombin-antithrombin III (TAT) complexes and antithrombin III (AT III) in amniotic fluid and blood plasma of 39 parturient women. TAT was measured by ELISA. Partigen plates were used for measuring the antigen of AT III, and activity was determined using chromogenic substrate. While AT III activity and AT III antigen were below 20% of plasma values, TAT concentration was 2–4 times higher in amniotic fluid than in blood plasma (over twice at the onset of labour, i.e. 54.2 ± 26.4 and 20.7 ± 10.7 ng/ml, and approximately 4 times after childbirth, i.e. 108.9 ± 49.2 ng/ml in amniotic fluid and 27.8 ± 13.2 ng/ml in blood plasma, respectively). We have concluded that thrombin generation and TAT formation in amniotic fluid are of significantly higher intensity than in plasma, and they increase during labour.

Changes in the fibrinolytic system of parturient women have so far been only partially documented. Our main questions were whether and how the concentration of tissue plasminogen activator (tPA) and plasminogen activator inhibitors of type 1 (PAI-1) and type 2 (PAI-2) change in the plasma throughout normal labor. The study group consisted of 38 women with normal pregnancy, delivering at term. The concentration of antigens tPA, PAI-1 and PAI-2 in plasma was tested by enzyme-linked immuno-sorbent assay method, and the activity of PAI-1 by plasmin method. Results were analysed statistically. During labor the level of tPA antigen increases over two times: from 9.3 +/- 4.3 ng/ml before labor, to 23.3 +/- 9.6 ng/ml in the second stage of labor. Changes of PAI-1 antigen as well as its activity though noticeable, were not statistically significant. PAI-2 antigen level increased significantly in the third stage (146.3 +/- 58.7 ng/ml before labor, and 212.2 +/- 75.0 ng/ml after placenta expulsion). In summary the more significant change in the fibrinolytic system during labor is an increase of the level of tPA and PAI-2 antigens, but their peaks appear in different stages of labor. The predominance of PAIs over tPA is maintained throughout the whole labor, though on a lower level as can be inferred from the tPA/PAIs ratio.

We measured three selected components of the fibrinolytic system in amniotic fluid of 36 parturient women, i.e. the antigen of tissue plasminogen activator (tPA) and antigens of plasminogen activator inhibitor of type 1 (PAI-1) and type 2 (PAI-2). The ELISA method was used. During labour, the level of each of the studied antigens increases; tPA antigen increases over five times (0.91 ± 0.32 ng/ml before labour and 5.92 ± 1.83 ng/ml after childbirth), which is statistically significant, while at the same time the increase in PAI-1 and PAI-2 antigen levels is small and thus statistically insignificant. As the result of unequal changes, the prelabour dominance of PAIs over tPA decreases intra partum (tPA/PAIs ratio 1:1,038 before labour and 1:164 after childbirth), and yet the multiple dominance of PAIs over tPA remains.

No abstract