The authors note that current guidelines on the management of pregnant women with thrombophilia without previous VTE differ considerably in their recommendations on the use of thrombosis prophylaxis, due to the limitations of the available data. They sought to update previous meta-analyses and for the first time report absolute risks, to provide evidence to support updated guidelines.
Based on their findings, they make the following recommendations for thrombosis prophylaxis, based on a threshold of absolute VTE risk of 3% for each antepartum or postpartum period:
· Women with antithrombin deficiency or protein C deficiency: antepartum prophylaxis and prophylaxis up to six weeks post-partum for those with a positive family history of VTE.
· Women with homozygous factor V Leiden mutations: consider thrombosis prophylaxis in those with a family history and additional risk factors for VTE.
· Women with protein S deficiency and a positive family history: prophylaxis using low molecular weight heparins only up to six weeks post-partum.
· Women with heterozygous factor V Leiden or heterozygous prothrombin G20210A mutations (or compound mutations): clinical vigilance only is suggested.
They were unable to make any recommendations for women with homozygous prothrombin G20210A mutation because of the lack of cohort data and the poor correlation of odds ratios with absolute risks.
Additional personal risk factors for VTE such as obesity and immobilisation, should be taken into account when deciding on thrombosis prophylaxis in individual patients.