In this paper, a study of the demographic situation in the Republic of Mordovia is carried out. The main trends in the development of socio– economic processes were identified: low birth rate, high migration rate and population aging. Based on the correlation and regression analysis, the main factors affecting fertility were identified and a regression model was built. The paper examined the state of marriage and divorce in the territory of the Republic of Mordovia, the peculiarities of marriage, the age structure of the couple, the period of birth of the first child in the family.