D-dimer concentrations during normal pregnancy, as measured by ELISA.

In pregnant women a number of changes in blood clotting and fibrinolysis proteins have been reported so indicating the existence of a state of hypercoagulability. In addition to fibrinogen and antithrombin III (AT), D-dimer is frequently checked during pregnancy, in particular during at risk pregnancy, but the exact pattern of D-dimer modifications during uncomplicated pregnancy is not definitively described. The aim of this study was to establish the range values in three different periods of uncomplicated pregnancy (A: 1-20 wks; B: 21-30 wks; C: 31-40 wks). We measured plasma levels of D-dimer, clottable fibrinogen and AT in 108 consecutive normal pregnant women aged 16 to 42 years. In period A, the range of D-dimer values was 43-211 ng/mL, not different from controls, while fibrinogen levels were significantly higher (p < 0.05) than in matched non pregnant women. Mean D-dimer levels were higher in periods B (p < 0.05) and C (p < 0.05) vs period A. Similarly, mean fibrinogen levels were found more elevated in periods B and C vs period A (p < 0.05). A significant correlation was found between fibrinogen and D-dimer levels (p < 0.001). No differences in AT levels were found among the three periods of pregnancy. The results of this study indicate that levels of D-dimer up to 685 micrograms/L may be reached at the end of physiological pregnancy. This fact should be taken into account in the evaluation of hemostatic studies performed in uncomplicated and complicated pregnant women.