The impact of dalteparin (Fragmin (R)) on thrombin generation in pregnant women with venous thromboembolism: Significance of the factor V Leiden mutation

Hypercoagulability is observed in patients with inherited thrombophilia, e. g. factor V Leiden (FVL) mutation. Pregnancy represents a hypercoagulable s tate as well. This study addresses the effects of the FVL mutation on haemo static activation during pregnancy as indicated by prothrombin fragments (F 1+2). 233 pregnant women with no history of venous thromboembolism were stu died. Additionally, two patient groups (25 pregnant FVL carriers and 36 pre gnant women without thrombophilic diathesis) in whom low molecular weight h eparin (dalteparin) was used prophylactically against rethrombosis were inv estigated. None of the women developed clinical signs of venous thromboembolism during pregnancy or after delivery. Untreated women exhibited substantial hyperco agulability. F1+2 levels were similar in FVL carriers and non-carriers (dif ference n.s.). After sufficient adjustment for anti-factor Xa activity (gre ater than or equal to0.15; less than or equal to0.4 U/mL), heparinized wome n without any thrombophilic diathesis had significantly lower levels of F12 than untreated pregnant women. This was evident only in the first and sec ond trimenon (p <0.01). F1+2 levels in heparinized FVL carriers were quite similar to the levels observed in untreated pregnant women, however. In con clusion, our data support the thesis that in comparison to asymptomatic pat ients, thrombin generation is exaggerated in symptomatic FVL carriers. Coag ulation activation during pregnancy can he reduced by dalteparin.