The article presents an analysis of the detectability of the hemostasis gene F13 in pregnant women with premature birth (PB). The results of molecular genetic studies have shown that the mutant T allele and hetero/homozygous genotypes of the F13 polymorphism are one of the markers of an increased risk of thrombophilia in pregnant women with PB with complex subordination, while the functional G allele and the functionally favorable G/G genotype are protective markers for the development of pathology (χ2=2.15; p<0.14; OR=3.81; 95%CI 0.18 – 81.73).