Table 2: Anticoagulation recommendations published in the British Journal of Haematology, January 2001 [22].

High risk
On long-term anticoagulantsPregnancy-long thromboprophylaxis. Consider using 75 anti Xa units/kg 12 hourly. Continue treatment for 6 weeks postpartum.
Type 1 antithrombin deficiency
Type 2 reactive site antithrombin defect

Moderate risk
Previous precipitated VTE plus thrombophilic defectConsider antenatal thromboprophylaxis with 4000 to 5000 anti-Xa units of LMWH once daily, starting in either the first or second trimester and continuing for 6 weeks postpartum.
Previous unprecipitated VTE
Homozygous factor V Leiden plus FMH
Homozygous prothrombin gene mutation plus FMH
Heterozygous protein C deficiency plus FMH
Combination of thrombophilias

Slightly increased risk
Heterozygous protein S plus FMHConsider thromboprophylaxis after delivery for 6 weeks, particularly if other risk factors are present such as increased maternal age.
Heterozygous factor V Leiden plus FMH
Heterozygous prothrombin gene mutation plus FMH
Previous precipitated VTE, no thrombophilia

VTE = venous thromboembolism, LMWH = low molecular weight heparin, FMH = family medical history of VTE.