How does demographic transition change population?
The demographic transition model describes how death and birth rates shift from high to low levels during economic and social change.
Formation process and geographic mechanism
Initially both rates are high and growth is slow. Health, nutrition and infrastructure lower mortality first while births remain high, producing rapid growth. Education, urbanization, child survival and family preferences later reduce fertility. In the later stage both rates are low and age structure may be older.
Spatial outcomes, measurement and management
The model is a broad tendency, not a law that every country follows at the same speed. Migration, war, epidemics, policy and culture alter trajectories. Age pyramids reveal education, work and care needs beyond total population. Planning considers fertility together with life expectancy and net migration.