Demographic Transition




Mortality transition (lower)

  1. Improvements in the standard of living esp. quantity and quality of food.
  2. Improvements in public health measures e.g. draining of mosquito-infected swamps and securing clean water.
  3. Role of medical treatments in curing diseases.


Fertility transition (lower)

  1. Improved contraception
  2. Cultural shift in favour of fertility control.
  3. Although total fertility is not that much higher than desired fertility
  4. Economic growth --> lower desired fertility because of  1. lower mortality 2. income & substitution effects (where price of children is higher) esp. opp cost of women not working 3. Resource flows between parents and children 4. Quality-quantity trade-offs.

Replacement rate of fertility is roughly 2.1 children per women would require both an increase in fertility in developed countries and a decrease in fertility in developing countries.


  • Predict a generally declining world population growth rate stabilising at around 11 billion by about 2150.


  • In developing world mortality rate has fallen faster than fertility thus populations are still growing.


  • Low Total Fertility Rate (TFR) may be due to a tempo effect where women are delaying the age at which they have children however this can only explain 0.25 to 0.4 of the reduction.
  • Demographic momentum is where the number of fertile women boosts population growth even if the rate of fertility stays the same.
  • Demographic structure particularly the percentage of the population of working age is significant for GDP/capita. E.g. In US fraction of working age population is forecast to fall from 0.6 to 0.54 which owould in a 20 year period have a -0.5% effect on GDP/capita.
  • Composition effect means that world GDP is declining as a larger proportion of the worlds population is from poor countries.