Fertility has central importance in demographic analysis as births are vital component of population dynamics. Level and trend of fertility indicates the standard of development of nation. Female child plays most important role in fertility dynamics. She establishes the institution of family life, brings up the children and makes them good citizens. Her strength in totality contributes in the making of an ideal society and thus ideal country. The connection between birth of females and fertility or vice versa are the root of many explanations of demographic transition and in shaping of population distribution Это и многое другое вы найдете в книге On the Estimation of Fertility Parameters using Sample Surveys (Piyush Kant Rai and Hemlata Joshi)