Natural increase

What is natural increase?

Population natural increase (or natural change) is the difference between the number of deaths, and the number of births over a period of time.

If there are more births than deaths over a period, natural increase will have a positive contribution to population growth.

Absent of net overseas migration, if there are more deaths than births, the population will decline.

Australia’s current rate of natural increase

Official information about Australia’s level of natural increase is published in Australian Bureau of Statistics National, state and territory population. In the year ending June 2019, Australia’s population increased by around 381 thousand, or a growth rate of 1.5 per cent. In that year, Australia had around 305 thousand births, and 163 thousand deaths, leading to natural increase of 142 thousand people or 37 per cent of Australia’s total population growth.

Births, deaths and natural increase, 1988–⁠89 to 2018–⁠19
This chart shows Australia’s natural increase, its components (births, and deaths), and natural increase’s contribution to total population growth for the years 1988-89 to 2018-19. The contribution of natural increase to population growth, which peaked at over 80 per cent in the mid-1990s, has since fallen and has been around 40 per cent for the past decade.

Source: Australian Bureau of Statistics, National, state and territory population

Historically, natural increase has been the main driver of Australia’s population growth.

While the number of births in Australia has generally increased as the population has grown, the number of babies per woman (referred to as the total fertility rate or TFR) has steadily decreased over time.

Births and total fertility rate, Australia, 1981–⁠82 to 2017–⁠18
This chart compares the total fertility rate with the number of births in Australia in each financial year between 1981-82 and 2017-18. While the number of births in Australia has generally increased as the population has grown, the fertility rate has steadily decreased over time

Source: Australian Bureau of Statistics, Births, Australia

While natural increase’s contribution to population growth has fluctuated over time, as the fertility rate has decreased, and the population has aged, natural increase has contributed steadily less to population growth.

Role of mortality in natural increase

As Australia’s population has increased, so has the number of deaths. However, life expectancy continues to steadily increase for both men and women. In addition, age adjusted mortality rates in Australia continue to decrease. This means that people are less likely to die in each year of their life than previous generations. This is due to medical advances and improved safety measures.

Life expectancy at birth for males and females, 1990–⁠92 to 2016–⁠18

Source: Australian Bureau of Statistics, Life Tables 2019

The decrease in age-adjusted mortality has helped offset the decrease in fertility rates.

While natural increase is an important part of Australia’s population growth, there are some countries, such as Japan, who have in recent years had more deaths than births. Countries with more deaths than births, and without positive net overseas migration will experience population decline.