Longitudinal evaluation of markers of hemostasis in pregnancy

The aim of this study was to establish the physiologic changes in hemostasis during pregnancy and to find the association between the factor V Leiden mutation and adverse pregnancy outcome.

We investigated blood samples of 148 pregnant women during each trimester of pregnancy. We measured their serum concentrations of factors I, II, V, VII, VIII, IX, X, XI, XII, D-dimers, prothrombin time, INR, aPTT, activity of protein C and S, antithrombin III and platelet count. The pregnancy outcome of women with factor V Leiden mutation was compared to those without congenital thrombophilia.

Prothrombin time, INR and aPTT were significantly shorter. We found significantly higher plasma concentrations of fibrinogen and d-dimers and higher levels of activity of factor VII and X in the third trimester. No significant difference was found in protein C and antithrombin III activity. The protein S activity was lower in the second trimester and it increased in the third trimester. Although most of the clotting factors were rising during the pregnancy, there was no evidence of fibrinolytic overactivation. In our study, the carriership of factor V Leiden mutation did not affect the incidence of preeclampsia, eclampsia, intrauterine fetal death and venous thromboembolism. Placental abruption was rare.

Hemostatic changes in pregnancy are significant and essential, and have the potential to cause adverse pregnancy outcome. In addition, hypercoagulable state during pregnancy is considered to be physiological (Tab. 4, Ref. 36).