The Fibrinolytic Enzyme System of Human Blood Plasma in Pregnancy

Three groups of women were examined: non-pregnant, 2nd trimester, and 3rd trimester of pregnancy. The plasma concentrations of plasminogen, pro-activator, plasmin inhibitor, and urokinase inhibitor were measured. Plasminogen and proactivator were increased in the 2nd and 3rd trimesters, proactivator more than plasminogen; this is discussed in the light of the concept of proactivator as a distinct property of the plasminogen molecule. Plasmin inhibitor was increased both in the 2nd and 3rd trimesters, urokinase inhibitor only in the 3rd trimester.