POORER women, older women and smokers are at risk of having a pre-term baby, according to a new study that also highlights a danger among Aboriginal women.
Mothers from the most disadvantaged areas with the least resources face the greatest risk.
In these areas, the chance of having a baby at least three months early is 45 per cent higher than in the most privileged areas.
A third of mothers giving birth to significantly premature babies live in disadvantaged areas, but only 28.5 per cent overall live in such areas, according to the University of Sydney study published in the Australian and New Zealand Journal of Public Health.
The researchers analysed births in the 10 years to 2004 to assess the link between pre-term birth and low socioeconomic status.
"Our study found a strong association between socioeconomic deprivation and an increasing risk of pre-term birth," said lead author Deborah Donoghue.
The risk of having a pre-term baby was also significantly higher for older mothers and Aboriginal women, she said.