APC resistance and other haemostatic variables during pregnancy and puerperium

Forty-eight healthy pregnant women were studied prospectively and longitudi nally. Blood sampling was performed at 10-15, 23-25, 32-34 and 38-40 weeks of gestation, within one week and at eight weeks postpartum. Classic and mo dified activated protein C ratio decreased as pregnancy progressed. In the third trimester 92% of the ratios measured with the classic test were above the lower reference level whereas all modified test ratios were normal. Sl ight activation of blood coagulation was shown with increased levels of pro thrombin fragment 1+2, soluble fibrin and D-dimer, Fibrinogen, factor VIII and plasminogen activator inhibitor type 1 and type 2 increased. Protein S and tissue plasminogen activator activity decreased. Protein C remained unc hanged. No correlation was found between the decrease in classic APC ratio and changes in factor VIII, fibrinogen, protein S, prothrombin fragment 1+2 or soluble fibrin, nor between the increase in soluble fibrin and changes in prothrombin fragment 1+2, fibrinogen and D-dimer.