Fertility rates method

Birth statistics can be reported as a crude birth rate, age specific fertility rate, total fertility rate or general fertility rate.

The crude birth rate is one of the main demographic statistics describing fertility. It is calculated as the number of live births in a year per 1,000 population. The denominator is the mid-year estimated resident population (ERP) in a calendar year.

Age specific fertility rates are calculated by dividing the number of live births in each age group by the total female population (in thousands) in each age group.

The total fertility rate (TFR) represents the number of children a female would bear during her lifetime if she experienced the current age-specific fertility rates at each age of her reproductive life (ABS Cat no 3301). It corresponds with the concept of an average completed family size. The TFR is calculated as the sum of age-specific fertility rates in one-year age groups, consequently reported age specific rates per 1,000 for 5-year age groups must be multiplied by 5 and divided by 1,000 when calculating the TFR. A replacement TFR for a population is equal to 2.0.

The general fertility rate is the least refined measure of fertility in a given population, used when the specific ages of mothers are not known. The numerator is the number of live births in a year and the denominator is the number of females of child bearing age. The definition of childbearing age varies between jurisdictions. In Australia it is defined as 15-49 years, however many countries adopt 15-44 years in their calculations (for example, the USA) and consequently the rates may not be comparable between countries (Last 2001).

References

Australian Bureau of Statistics. Births, Australia Cat no 3301.0. Canberra: ABS . Available at http://www.abs.gov.au/ausstats/abs@.nsf/mf/3301.0

Last JM (eds). A dictionary of epidemiology. Fourth edition. New York: Oxford University Press. Inc, 2001.