The problem of prevention of complicated course of pregnancy and childbirth takes a leading place in modern obstetrics and perinatology. The authors conducted a profound analysis of numerous clinical studies in the area of folate metabolism in general, its role in the reproductive health of women, gestational complications, and the formation of fetal pathology. The significance of folic acid deficiency which is related to diet peculiarities, to insufficient enzymes intake, as well as to defects in folate exchange genes, which determine the reduced enzyme activity, is evaluated. In recent years, there has been much evidence that mutant homozygous (TT) and heterozygous (CT) genotypes are much more common among women with complicated pregnancies. Genetic deficiency of the key enzyme of the folate cycle – methylene-tetra-hydro-folate-reductase (MTHFR) is one of the reasons of hyperhomocysteinemia that has a pronounced toxic effect, damages the endothelial lining of the blood vessels and triggers a disorder of the processes of coagulation. Hyperhomocysteinemia has a big influence on the development of pregnancy complications, which depend on microcirculation, starting with spontaneous miscarriage in the first trimester of pregnancy and ending with preeclampsia, premature placental abruption and intrauterine fetal death. The consequences of the folate cycle problems at different stages can be congenital malformations of the fetus, especially defects of the neural tube. The importance of folic acid in the pathogenetic mechanisms of anemia is described. An interesting question is the role of low-functional alleles of folate genes in reproductive function disorders: under condition of infertility and miscarriage. The presented literature review is a reasonable conclusion for the need of further study of folate metabolism, taking into account genetic predisposition and other components.

A special attention is paid to thyroid gland functioning during pregnancy. It is explained by the fact that pregnancy is a powerful factor which can lead to a manifestation of diseases of the thyroid gland. Cells of the thyroid gland are capable to acquire iodine from food and to synthesize the thyroid hormones participating in all exchange processes both of a pregnant woman and the fetus. For the purpose of studying the features of functioning of the thyroid gland and a number of metabolic processes from ecological positions (in the conditions of city and rural areas) and terms of gestation, 945 pregnant women of the Amur region were examined. Insufficiency of iodine in blood at 95.3% of inhabitants of the city area and at 98.7% of women of rural areas was revealed. It was mainly very severely expressed (47.9 and 55.5%, respectively). Taking into account these data, the assessment of a functional state of the thyroid status was done. Some indicators of lipid profile and carbohydrate ranges were defined. Disturbance of functional activity of mitochondrial dehydrogenases of immunocompetent cells (lymphocytes) in pregnant women of the Amur region in the form of oxidation-reduction reactions imbalance were revealed, which as a whole can badly influence the course of pregnancy and its outcome.