Hypothesis/aims of study. To date, one of the most important avenues of research in the field of reproductive medicine is the searching for new biochemical markers of oocyte quality and the prediction of the effectiveness of in vitro fertilization (IVF) protocols. The aim of this study was to assess the effect of relaxin levels in blood serum and follicular fluid on the efficiency of ovulation stimulation, fertilization, and characteristics of the embryos. Study design, materials and methods. This prospective randomized cohort study included 11 patients undergoing infertility treatment in a superovulation stimulation protocol using gonadotropin-releasing hormone antagonists. Age, body mass index, hormonal status, ovarian response, endometrial thickness and structure, the number and quality of oocytes and embryos, as well as fertilization efficiency were assessed. The level of relaxin in blood serum and follicular fluid samples was determined on the day of transvaginal follicle puncture using enzyme immunoassay. Results. A correlation between follicular fluid relaxin levels and body mass index, age, the number of oocytes, and their fertilization efficiency (p 0.05) was established. Changes in follicular fluid relaxin level were revealed depending on the gonadotropin preparations (p 0.05) and triggers of final maturation of oocytes (p 0.05). The tendency of the effect of gonadotropin doses on circulating relaxin levels, and of the hormone itself on endometrial thickness and the quality of oocytes was determined. Conclusion. Determination of the relaxin concentration can be considered as a promising method for predicting the result of ovarian stimulation and the efficiency of fertilization in IVF protocols.

This article presents the latest research data on the role of vitamin K in the implementation of its multiple non-classical extra-coagulation effects associated with the regulation of a number of physiological and pathological processes in the human body. In recent years, numerous studies have been performed on vitamin K function to better understand the effects of this micronutrient and its significance in various biological reactions. Vitamin K is well known to be a cofactor of the -carboxylation of a number of proteins, which is necessary for their activation and is part of the so-called vitamin K cycle. The cycle enzymes, metabolites and vitamin K-dependent proteins are identified and expressed in many cells and tissues of the human body: skin, lungs, liver, kidneys, vascular endothelium, nervous and bone tissues, reproductive (endometrium, ovaries, placenta) and immune systems. There were analyzed the main mechanisms of vitamin K action through vitamin K-dependent proteins. The results of epidemiological and experimental studies prove the association of reduced vitamin K levels with the increased risk of cardiovascular diseases, overall mortality, insulin resistance, metabolic syndrome, type 2 diabetes mellitus, progression of rheumatoid arthritis and osteoporosis. On the contrary, vitamin K increased intake has a positive effect on the immune and nervous systems, as well as on a number of other somatic pathologies, including breakdowns in the reproductive sphere. These data confirm the multifunctional role of vitamin K in various organs and systems of organism, presenting as high potential further studies in the field of determining vitamin K levels.