AIMEvaluation of alterations of immune response regulation and possible risk of antenatal development of fetus in postvaccination period in pregnant women immunized against influenza A (H1N1).MATERIALS AND METHODSWomen were vaccinated with MonoGrippol plus vaccine in the II trimester of physiological pregnancy. At certain intervals ofthe vaccination period (before the vaccination, 7 and 30 days after the vaccination) major biochemical markers in blood sera (alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, alkaline phosphatase, creatinine, urea) and levels of key cytokines in spontaneous and stimulated test (IL-1alpha, IL-1RA, IL-2, IL-4, IL-10, IFNgamma, TNFalpha) were evaluated. Vaccination safety for the fetus and trophoblast development was evaluated by using human chorionic gonadotropin (HCG), alpha-fetoprotein (AFP) and trophoblasitc beta-1-glycoprotein (TBG) levels.RESULTSDuring vaccination in 13% of cases mild local reactions were noted, in 26.1%--general systemic reactions in the form of weakness, dizziness and headaches. Levels of major biochemical markers at days 7 and 30 after the vaccination did not have any significant difference from the initial values (p > 0.05). Cytokine levels in spontaneous and stimulated tests also did not change significantly. Markers of the course of pregnancy and fetus development (HCG, AFP and TBG) in the two groups observed had comparable values.CONCLUSIONVaccination of pregnant women against influenza A (H1N1) by Russian subunit formulation (MonoGrippol plus) showed reactogenicity comparable to control group by the level of influence on general metabolic and immunologic homeostasis and on the course of pregnancy, which is an evidence of its safety.