The association between hereditary thrombophilias and pregnancy loss.

The correlation between hereditary thrombophilia and fetal loss is supported by several observations. In murine models, the protein C system has been shown to be essential for the maintenance of pregnancy, as it indirectly acts as a growth factor for trophoblast cells and protects them from apoptosis. In humans, it has been shown that the placenta replaces the yolk sac as an essential source of blood supply to the embryo during the 8th and 9th weeks of gestation. Furthermore, meta-analysis of epidemiological data demonstrates a correlation between thrombophilic polymorphisms such as factor V Leiden and prothrombin 20210G-->A and isolated or recurrent fetal losses. Finally, therapeutic non-controlled trials indicate the benefits and safety of low-molecular weight heparins as secondary prophylaxis. However, it is still necessary to further clarify the association between thrombophilia and fetal loss, especially during a first pregnancy, with regard to the type of pregnancy loss and with respect to other related factors.