QUANTITATION OF THE THROMBOTIC EFFECTS IN ARTERY AND VEIN OF THE INCREASE IN COAGULATION-FACTORS DURING NORMAL-PREGNANCY IN THE RAT

Coagulation factors increase and fibrinolysin activity decreases in pr egnant women. While the nett change in thrombotic tendency is unmeasur ed, venous thromboembolism increases five-fold in this group. We measu red thrombus formation in vein and artery on standard platinum wires i n 45 near-term pregnant rats, 19 pregnant for the first time and 26 fo r the second time, and in 33 never-pregnant controls. No significant i ncrease in arterial thrombus occurred in the pregnant rats. Venous thr ombus, however, increased by 65% in rats pregnant for the first time a nd 176% in those pregnant for the second time, compared to never-pregn ant animals. Their mean increase in coagulation factors VIII, X, V, VI I and II varied from 165 to 268%. Factor VIII level (r=0.59, p<0.05) c orrelated with venous thrombosis level,but the rarity of spontaneous t hrombosis did not permit the limits of risk to be determined. Factors VII, X and V showed little correlation with thrombus weight (r=<0.16) and Factor II an insignificant one. Monitoring factor WI levels in pre gnant women might help identify a group at risk of thromboembolism and establish a threshold for prophylactic intervention. (C) 1997 Elsevie r Science Ltd.