Blood coagulation and fibrinolysis during normal pregnancy.

Fifty-six pregnant women (gestational age 6-40 weeks) were evaluated for their coagulation activation (fibrin monomers and thrombin-antithrombin III complex) and for their fibrinolysis profile by determining tissue plasminogen activator, plasminogen activator inhibitor, plasminogen, alpha 2-antiplasmin and D-dimer. Fibrin monomers and thrombin-antithrombin III complexes were found to be significantly increasing with gestational age. All the fibrinolytic parameters showed a steady growth with the progress of the pregnancy, with the exception of tissue plasminogen activator which showed a significant decrease with gestational age, but mainly within the reference range. These results suggest a stimulation of the coagulation system and an activation of fibrinolysis with ongoing pregnancy, although the increasing alpha 2-antiplasmin and plasminogen levels and the decreasing tissue plasminogen activator concentrations do not conform to this trend.