PROS1 and fetal growth restriction: In our systematic review, one study [20], which tested patients for protein C activity, protein S activity, antithrombin III activity, factor VIII, active protein C resistance, prothrombin and active partial thromboplastin time, factor V Leiden, MTHFR C677T and A1298C as well as prothrombin G20210A mutations, revealed a significant association between factor V Leiden homozygote mutation, for the coexistence of factor V Leiden mutation with MTHFR mutation and IUGR, respectively; the prevalence of IUGR in these groups being between 33.3–83.4%.