Aboriginal infant mortality rates

Infant mortality is accepted as an important indicator of population health and its routine reporting is an essential element of vital statistics. The infant mortality rate (IMR) is calculated by the number of infant deaths in year X divided by the number of births in the same year.

Although the infant mortality rate is a simple calculation, there are many moving parts in both the births and deaths data making data quality issues difficult to identify and resolve. For example, data is usually reported as year of registration, but can also be reported as year of occurrence. Both these have differing levels of reporting lag, which is also different between births and deaths, and between the Aboriginal and non-Aboriginal groups. Further, there are issues with under-identification of Aboriginality in both births and mortality data. Additionally, there can be discrepancies due events being reported by state of residence of the person or state of facility for event. This creates complexity in interpreting IMRs especially for comparison over time and even more so the relative differences in measuring the gap between the Aboriginal and non-Aboriginal populations.

For example, in a particular year, a small increase in the number of Aboriginal infant deaths coupled with a reduction in the number of births registered in that year, can cause the Aboriginal infant mortality rate to increase while the non-Aboriginal rate will remain relatively stable. 

The Australian Bureau of Statistics (ABS) reports on infant mortality rates for the Aboriginal population in NSW, Queensland, South Australia, Western Australia and the Northern Territory. Other states and territories are excluded due to small numbers of registered Indigenous deaths.

The ABS urges caution in assessing trends and warns against over-interpretation of data based on the small number of infant deaths involved (see ABS. Deaths.). Consequently, a  three-year rolling average, a more robust measure of the IMR, is provided to assist interpretation.