Demographic transition and population control

The demographic transition theory describes how a region's population changes as its society moves from rural, agricultural and illiterate to urban, industrial and literate. It passes from high births and high deaths to low births and low deaths, in three stages:

• Stage I: both birth and death rates are high. People have many children, partly to make up for those who die from epidemics and food shortages, and to work on the farms. Population grows slowly. Life expectancy is low, and most people are illiterate and poor. Two hundred years ago, all countries of the world were at this stage.
• Stage II: death rates fall first, thanks to better health care and sanitation, while birth rates stay high. The gap between them is wide, so population grows fastest here.
• Stage III: both rates are low. People are urban, literate and have high technical know-how, and they deliberately keep their families small. Population becomes stable, or grows only slowly.

So, in short: deaths fall first, and births follow later.

Controlling population growth. Family planning helps limit growth and improve women's health. Measures include making contraceptives freely available, tax disincentives for large families, and public awareness campaigns.

Concern about population is old. In 1798, the economist Thomas Malthus argued that population would grow faster than the food supply, unless checked by famine, disease or war.