The aim of the article is to align a hierarchy of factors and analyze the reasons for the decline in the birth rate among the urban population of Krasnoyarsk Krai in the late 1950s - early 1990s. The source base is the materials of the current population count for Krasnoyarsk Krai and the Russian Soviet Federative Socialist Republic. An attempt is made to distinguish between the concepts of "fertility factor" and "cause of fertility". The reasons in the article mean those changes in public consciousness that led to the abandonment of the birth of children or a decrease in their number within the framework of intrafamily birth control. Factors mean objective changes in social life, which led to a change in the component of social consciousness associated with reproductive behavior. The article shows that the decline in the birth rate in the period under review was of a landslide nature. The highest rates of this process were observed in the 1960s. The author proves that the birth rate in the region decreased more than the average for the RSFSR, which was largely due to the initially higher level and higher rates of industrial development of the region in the period under review. Changes in public consciousness, manifested in the restructuring of the system of values, goals, needs and priorities of individuals and related norms and models of sexual, matrimonial, pro-creative behavior, are designated as the main fundamental reason for the decline in the birth rate. The main factor in fertility decline highlighted the transition to the urban way of life, greatly accelerated the forced industrial development of Krasnoyarsk Krai. Another determining factor was a decrease in the need for children due to significant successes in the striving against child mortality in the context of the withering away of the family's production function. The author proves that children lost their importance, as evidenced by a very high abortion rate and a decline in the number of children in the family. These changes are interpreted as the final approval of the pronounced K reproductive strategy. The important role of the structural factor is emphasized, taking into account the fact that its negative impact on the birth rate in the region was manifested to a lesser extent than on average in the urban area of the RSFSR due to the remoteness from the fronts of the Great Patriotic War and youth migration to industrial facilities under construction in the period under review, which led to a "leveling" of the age-and-gender structure. The author hypothesizes that the remaining factors are either connected or are parts of the mentioned ones, and that only integral systemic changes in the most significant aspects of social life (the level and prevailing type of production, women's involvement in the economy, the state of social infrastructure, etc.) that altered public consciousness can be interpreted as the causes of factors of declining fertility.
