The demographic transition theory is an empirical theory based on actual population transition experiences of industrialised countries through the eighteenth and nineteenth centuries. It is considered as an important model which establishes a relation between economic (industrial) development and population changes. It is built on the classical economics model which treats population as endogenous to development. Population becomes the key indicator of development of the economy in that low population growth rate shows a higher level of development after industrialisation has begun. Although this theory has been proposed as early as 1929 by Thompson, it was only in 1945 that Frank W. Notestein put it a mature form by explaining the changes in fertility and mortality. The demographic transition theory proposes five stages in the population transition corresponding to levels of economic development through industrialisation.

Stage1: The first stage is called the ‘high stationery’ stage characterized by very high birth rate and very high death rate. Life expectancy is low. The population size is small and almost stationery. Society is characterized by low levels of economic development and industrialisation is yet to begin. Pre-industrial Europe was in this stage. During the pre-industrial stage, societies have high birth and death rates. Because both rates are high, population grows slowly and also tends to be very young: many people are born, but few live very long. In pre-industrial society, children are an economic benefit to families, reinforcing high birth rates. Children contribute to the household economy by carrying water