What Is the Demographic Transition Model?

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Demographic transition is a model used to represent the movement of high birth and death rates to low birth and death rates as a country develops from a pre-industrial to an industrialized economic system. It works on the premise that birth and death rates are connected to and correlate with stages of industrial development. The demographic transition model is sometimes referred to as "DTM" and is based on historical data and trends. 

The Four Stages of Transition 

Demographic transition involves four stages.

  • Stage 1: Death rates and birth rates are high and are roughly in balance, a common condition of a pre-industrial society. Population growth is very slow, influenced in part by the availability of food. The U.S. was said to be in Stage 1 in the 19th century. 
  • Stage 2: This is the "developing country" phase. Death rates drop rapidly due to improvements in food supply and sanitation, which increases life spans and reduces disease. Without a corresponding fall in birth rates, countries in this stage experience a large increase in population.
  • Stage 3: Birth rates fall due to access to contraception, increases in wages, urbanization, an increase in the status and education of women, and other social changes. Population growth begins to level off. Mexico is believed to be in this stage in the early decades of the millennium. Northern Europe entered this stage in the later part of the 19th century. 
  • Stage 4: Birth rates and death rates are both low in this stage. People born during Stage 2 are now beginning to age and require the support of a dwindling working population. Birth rates may drop below replacement level, considered to be two children per family. This leads to a shrinking population. Death rates may remain consistently low, or they may increase slightly due to increases in lifestyle diseases linked to low exercise levels and high obesity. Sweden has reached this stage in the 21st century. 

The Fifth Stage of Transition 

Some theorists include a fifth stage in which fertility rates begin to transition again to either above or below that which is necessary to replace the percentage of the population that is lost to death. Some say fertility levels decrease during this stage while others hypothesize that they increase. Rates are expected to increase populations in Mexico, India and the U.S. in the 21st century, and to decrease populations in Australia and China. Birth and death rates largely plateaued in most developed nations in the late 1900s. 

The Timetable

There is no prescribed time within which these stages should or must take place to fit the model. Some countries, like Brazil and China, have moved through them quickly due to rapid economic changes within their borders. Other countries may languish in Stage 2 for a much longer period due to development challenges and diseases like AIDS. Additionally, other factors not considered in the DTM can affect the population. Migration and immigration are not included in this model and can affect the population. 

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Crossman, Ashley. "What Is the Demographic Transition Model?" ThoughtCo, Feb. 16, 2021, thoughtco.com/demographic-transition-definition-3026248. Crossman, Ashley. (2021, February 16). What Is the Demographic Transition Model? Retrieved from https://www.thoughtco.com/demographic-transition-definition-3026248 Crossman, Ashley. "What Is the Demographic Transition Model?" ThoughtCo. https://www.thoughtco.com/demographic-transition-definition-3026248 (accessed June 10, 2023).