The book presents the key concepts and indicators for studying reproductive behavior and the state of research in this field in Bulgaria. It analyzes trends in fertility rates and their impact on the demographic structure of the population, and seeks to explain the causes of the negative trends in demographic processes in the country. Data are presented on births and abortions, marriage and families, marital and non-marital births, and their various indicators during the second half of the 20th century. Based on data from population censuses and sample surveys, the book examines changes in reproductive behavior, reproductive attitudes, norms, and differences according to the sociodemographic characteristics of women. Special attention is given to reproductive values, as well as to the factors that determine reproductive attitudes. The information in the book provides a rich "database" for future research by statisticians, demographers, medical professionals, and other specialists.