Birthweight is an important indicator of an infant’s health. Nine in ten babies (92%) were born with a normal birthweight (birthweight between 2,500 and 4,499 grams). Around 1% of babies are high birthweight (birthweight of 4,500 grams or more).

Low birthweight (birthweight less than 2,500 grams) has been associated with increases in illness and death in infancy and into adulthood. In 2020, 7.1% of all babies were low birthweight – 6.5% of liveborn babies and 85% of stillborn babies.

The data visualisation below presents data on the birthweight of liveborn babies, by selected maternal and baby characteristics, for 2020. Click the trend button to see how data has changed over an 11-year period (where available).

The figure shows a bar chart of the proportion of liveborn babies by birthweight by a range of topics for 2020. The figure also shows a line graph of trends within birthweight categories by a range of topics over 2010 to 2020. In 2020, 6.5% or 19,115 liveborn babies had a low birthweight.

Over 1 in 7 (15%) liveborn low birthweight babies weighed less than 1,500 grams and 6.3% of liveborn low birthweight babies weighed less than 1,000 grams.

Pre-term birth is closely linked with low birthweight – over two thirds (70%) of liveborn low birthweight babies were pre-term (gestational age before 37 completed weeks) and more than half (57%) 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 (7.8%) than babies born to mothers who lived in the least disadvantaged areas (5.4%).

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%).

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.


OECD (Organisation for Economic Co-operation and Development) (2019) Health at a glance 2019: OECD indicators, OECD, accessed 13 April 2021.