Maternal age
The Aboriginal and Torres Strait Islander population has a younger age structure than the non-Indigenous population. Figure 1 shows the difference in the age profile of Aboriginal and Torres Strait Islander and non-Indigenous females according to the ABS 2021 Census Estimated Residential Population for Indigenous Australians (ABS 2021).
Figure 1: Australian female population distribution, by Indigenous status and age group, 2021
Source: AIHW analysis of ABS 2021.
In 2020 – reflecting these differences in age structure – the mean age of Aboriginal and Torres Strait Islander females who gave birth was 26.5 years, the median age was 26 years, and the most common maternal age group was 25-29 years (30%). In comparison, the mean age of non-Indigenous females who gave birth was 31.2 years, the median age was 31 years, and the most common maternal age group was 30-34 years (38%).
Whilst most mothers have normal pregnancies and healthy babies regardless of age, mothers aged under 20 years and those aged 40 years and over can have an increased risk of maternal and infant complications and adverse pregnancy outcomes (AIHW 2022).
This report shows that Aboriginal and Torres Strait Islander females who gave birth and were aged under 20 years were more likely than other maternal age groups to smoke at any time during pregnancy or in the first 20 weeks of pregnancy, be underweight, have an episiotomy and give birth to a baby who was of low birthweight or small for gestational age.
Aboriginal and Torres Strait Islander mothers who were aged over 40 years were more likely than other maternal age groups to be obese, have pre-existing or gestational diabetes, have induced labour and give birth to a baby who was pre-term.
In 2020, a higher proportion of Aboriginal and Torres Strait Islander females who gave birth were aged under 20 years (11%) compared with non-Indigenous females (1.3%). Conversely, non-Indigenous females were more than twice as likely to be aged 40 years and over (4.6% compared with 2.0%).
Over time, the age of Aboriginal and Torres Strait Islander mothers has increased (from a mean of 24.9 years in 2005 to 26.5 years in 2020), and the proportion who gave birth aged under 20 years has halved (from 22% in 2005 to 11% in 2020).
The data visualisation below shows the proportion of Aboriginal and Torres Strait Islander and non-Indigenous females who gave birth by maternal age group, mean age and median age from 2005.