Demographic transition

The demographic transition model

The demographic transition describes how a country’s birth and death rates change as it develops from a traditional agricultural society into a modern industrial one. It was first described by Warren Thompson (1929) and later developed by Frank Notestein.

• Stage 1 (high stationary): both birth rate and death rate are high. Population grows slowly or not at all. Causes: poor food supply, disease, no modern medicine. No country today is fully in this stage.
• Stage 2 (early expanding): the death rate falls fast because of better food, clean water, sanitation, vaccines and medicine, but the birth rate stays high. Population grows rapidly (the “population explosion”).
• Stage 3 (late expanding): the birth rate also starts to fall: more education (especially of girls), urbanisation, family planning, lower child deaths and changing jobs make smaller families attractive. Growth slows.
• Stage 4 (low stationary): both rates are low. Population is large but stable.
• Stage 5 (declining), added by some writers: birth rate falls below death rate and the population shrinks (e.g. Japan in recent years).

Factors in the transition

• Falling death rate: sanitation, safe water, vaccines, antibiotics, better nutrition.
• Falling birth rate: female education and work, urban living, contraception, old-age security, lower infant mortality (parents no longer need many children to make sure some survive).

India’s death rate fell sharply after 1947 while birth rates fell more slowly, so India passed through the rapid-growth phase; its birth rate has fallen steadily since.

Key points

• Stage 1: high birth, high death → slow growth.
• Stage 2: falling death, high birth → fastest growth.
• Stage 3: falling birth → slowing growth.
• Stage 4: low birth, low death → stable.
• The gap between the birth and death rates gives the natural growth rate.

Exam tips

The most common question asks in which stage population grows fastest (Stage 2). Others ask which factor causes the death rate to fall, or which causes the birth rate to fall.

Common mistakes

• Saying birth rate falls first; usually the death rate falls first.
• Thinking Stage 4 means a small population; it is large but stable.
• Treating the model as an exact law; countries pass through it at different speeds.