[Pregnancy-associated venous thrombosis in women with hereditary heterozygous factor V Leiden and/or factor II gene mutations].

The risk of venous thromboembolism (VTE) in pregnant women with heterozygous factor V Leiden and/or heterozygous factor II 20210A gene mutations is poorly documented, and the need for prophylaxis is therefore controversial. We retrospectively studied 208 women with hereditary thrombophilia (heterozygous FV Leiden and/or factor II gene mutations), who had a total of 406 full-term pregnancies, including 10 with thromboprophylaxis. The ante- and post-partum incidence of VTE was significantly higher in women with both mutations (17.8 %) than in women with FII gene mutation alone (6.2%) p = 0.003. In contrast, there was no significant difference between women with FV+FII mutation and those with FV mutations alone (10%). Thus, the two most common hereditary risk factors for thrombophilia seem to have an additive rather than a synergistic effect on the antepartum/post-partum risk of VTE. In contrast, a previous history of VTE before pregnancy in women with both the FV and the FII gene mutations was associated with a very high risk of VTE (50%). The incidence of VTE was higher during the post-partum period than the ante-partum period. There was no significant difference in the incidence of fetal loss in the three groups, but this was not a primary endpoint. These results, obtained in a single center, have implications for VTE prophylaxis. Routine use of LMWH is not indicated during pregnancy in asymptomatic women with a single mutation. In contrast, it is justified throughout pregnancy in women with both mutations and a history of venous thrombosis. Regarding asymptomatic women with both mutations, the need for prophylaxis during part or all of the pregnancy should be weighed up on an individual basis. In the post-partum period, there is a consensus on the use of LMWH for 6 weeks in women with single or dual mutations associated with thrombophilia.