Four Distinct Phases of Demographic Transition
Demographic transition takes place in four distinct phases.
1. Re-industrial stage in which harsh living conditions lead to high birth rates to compensate for high infant mortality and high death rates. This leads to little population growth.
2. Transitional stage which starts shortly after industrialisation begins. At this stage death rates drop as a result of increased food production and better sanitation and health care. Birth rates remain high, population grows at a high rate (2.5-3% per year) for a long period but begins to level off later as living conditions improve.
3. Industrial stage in which industrialisation is widespread. Birth rates fall and eventually approach death rates, as people after moving to cities realise that it is more to their advantage to raise small families in an expanding economy.
4. Post-industrial stage in which birth rate equals death rate thus leading to zero population growth (ZPG) Birth rate continues to fall so that the population size begins to decline slowly.