INFLUENCE OF PREGNANCY UPON BLOOD-COAGULATION AND PLASMA FIBRINOLYTIC ENZYME FUNCTION

Fibrinogen catabolism has been studied in 27 patients from early pregnancy through delivery and up to 4 months post partum using the noninvasive technique of plasma fibrinogen chromatography. This technique quantifies in plasma the percentage and concentration of high-molecular weight fibrinogen or fibrinogen/fibrin complexes (HMWFC), which reflect the rate of fibrin formation in vivo, native fibrinogen, and derivatives of fibrinogen smaller than the native molecule resulting from the actions of the enzyme plasmin on fibrinogen, an assay reflecting the rate of fibrinogenolysis. Plasma fibrinogen chromatographic findings were similar to control findings during the first gestational month but during the second gestational month plasma HMWFC percentage and concentration were elevated twofold to threefold over control values and thereafter increased with gestational age, being fivefold control values prior to delivery. Plasma fibrinogen increased by the third month and its increase was significantly (p < 0.01) correlated with increase of plasma HMWFC. Fibrinogen first-derivative concentration was mildly elevated during pregnancy. These results demonstrate that intravascular fibrin deposition, presumably involving the uteroplacental circulation, is the earliest and most persistent alteration in blood coagulation function noted during pregnancy. Further, the fivefold increase in fibrin deposition during pregnancy over the physiologic, nonpregnant state is accompanied by a significant increase in compensatory fibrinolysis. © 1979.