Demographic transition

Demographic transition (DT) refers to the transition from high birth and death rates to lower birth and death rates as a country develops from a pre-industrial to an industrialized economic system. This is typically demonstrated through a demographic transition model (DTM). The theory is based on an interpretation of demographic history developed in 1929 by the American demographer Warren Thompson (1887–1973). Thompson observed changes, or transitions, in birth and death rates in industrialized societies over the previous 200 years. Most developed countries are in stage 3 or 4 of the model; most of developing countries have reached stage 2 or stage 3. The major (relative) exceptions are some poor countries, mainly in sub-Saharan Africa and some Middle Eastern countries, which are poor or affected by government policy or civil strife, notably Pakistan, Palestinian territories, Yemen, and Afghanistan. Adolphe Landry of France made similar observations on demographic patterns and population growth potential. In the 1940s and 1950s Frank W. Notestein developed a more formal theory of demographic transition.