Demographic transition
In demographics, the term demographic transition is used to describe the transition from high birth rates and death rates to low birth and death rates that occurs as part of the economic development of a country from a pre-industrial to a post-industrial economy.
In the midst of a demographic transition, death rates drop without a corresponding fall in birth rates, and countries undergoing this process experience a large increase in population.
At the end of this process, both rates are lower, and many rich western countries now have a population that is static or shrinking.