Birthweight
Birthweight is an important indicator of an infant’s health. In 2021, over 9 in 10 babies (92%) were born with a normal birthweight (birthweight between 2,500 and 4,499 grams); also referred to as 'healthy birthweight'. Around 1.2% of babies were high birthweight (birthweight of 4,500 grams or more).
Low birthweight (birthweight less than 2,500 grams) has been associated with an increased risk of illness and death in infancy and into adulthood. In 2021, 6.8% of all babies were low birthweight – 6.3% of liveborn babies and 82% of stillborn babies.
Figure 1 presents data on the birthweight of liveborn babies, by selected maternal and baby characteristics, for 2021. Select the trend button to see how data has changed over an 11-year period (where available).
Figure 1: Proportion of liveborn babies, by birthweight and selected topic
Bar chart shows birthweight by selected topics and a line graph shows topic trends between 2011 and 2021.
Over 1 in 7 (15%) liveborn low birthweight babies weighed less than 1,500 grams and 6.5% of liveborn low birthweight babies weighed less than 1,000 grams.
Pre-term birth is closely linked with low birthweight – over two thirds (71%) of liveborn low birthweight babies were pre-term (gestational age before 37 completed weeks) and more than half (56%) of pre-term babies were of low birthweight.
The proportion of liveborn low birthweight babies was higher among babies born to mothers who lived in the most disadvantaged areas (7.5%) than babies born to mothers who lived in the least disadvantaged areas (5.2%).
Internationally, the proportion of low birthweight babies in Australia in 2018 or nearest year (6.7%), was slightly higher than the OECD average (6.6%) (OECD 2019).
Figure 2 presents the number and proportion of liveborn babies who were low birthweight, by PHN area and SA3, in 2021.
Figure 2: Proportion of liveborn babies who had a low birthweight, by selected geography
Map shows proportion of low birthweight babies by selected geographies and years.
For related information see National Core Maternity Indicator Small babies among births at or after 40 weeks of gestation.
For more information on birthweight see National Perinatal Data Collection annual update data table 3.9.
For more information on liveborn babies who were low birthweight by Primary Health Network area and Statistical Area Level 3 see National Perinatal Data Collection annual update data tables 5.5 and 5.11, respectively.
References
OECD (Organisation for Economic Co-operation and Development) (2019) Health at a glance 2019: OECD indicators, OECD, accessed 13 April 2021.