The demographic cycle, or population cycle, refers to the evolution over time of the population profile of a country, region or other defined geographical area. A population cycle theory has been postulated in terms of the socio-economic history of industrialized countries. Four stages of population change have been identified in the demographic cycle:
- the first high stationary phase marked by high birth and high death rates and relatively low population;
- the second phase with uneven population density due to increased urbanization and industrialization;
- the third phase where the birth and death rates are much lower resulting in a relatively steady population growth; and
- the fourth phase of population cycle which is characterized by stagnation or an actual decline in the total population of a country due to an excess of deaths over births.