The main causes of a change in population size

Changes to the size and structure of a population are caused by social, economic and political factors.

Social factors that affect population size and structure

Social factors include education, migration, healthcare and lifestyle. In 1948 the NHS was set up in the UK which led to increased life expectancy due to freely available healthcare to the population. In the UK, education about the health effects of smoking and alcohol have helped increase life expectancy.

Economic factors that affect population size and structure

Economic factors include the availability of jobs and wage levels which can affect migration to and from regions and countries. The attraction of higher wages has encouraged migration from many eastern European countries to the UK since 2004.

Political factors that affect population size and structure

Political factors that affect population size and structure include government population policies and civil war. Population policies like China’s One-Child Policy has reduced the rate of natural increase in the country, however, it has also led to an ageing population and a greater number of males than females in the country.

A civil war can lead to a decline in population, reduced population densities and can change the age-sex structure of a country with fewer males of fighting age due to deaths in the conflict.

Changes in birth and death rates and migration all have an impact on whether the population of a region or country is increasing or decreasing. Changes in birth and death rates affect the natural increase or decrease of a population. Migration can also affect this along with the structure of the population.

In the 21st century, population growth is starting to level off with birth and death rates in many countries, particularly HICs, being very low. In some countries such as Japan and Germany, birth rates have fallen below death rates leading to population decline. It is estimated that in the future, by 2050, birth rates will fall below death rates in three out of every four LICs.