"This study showed a steady and statistically significant decline in the proportion of women who reported drinking alcohol during pregnancy from 2007 to 2011," the article said.
It found that 34.8 percent of pregnant women surveyed reported drinking
in 2011 compared with 52.8 percent in 2007.
The proportion of women who drank alcohol after the first trimester also dropped sharply -- from 42.2 percent to 25.8 percent -- while the group which drank in each stage of pregnancy nearly halved -- from 20.9 percent to 11 percent.
But high-risk drinking (five or more standard drinks on any one occasion) did not change significantly over the five years, the "Griffith Study of Population Health: Environments for Health Living" revealed.
"Despite the overall decrease in alcohol consumption after the first trimester of pregnancy from 2007 to 2011, no significant decrease was found for women older than 35 years, single parents, those in the lowest household income quintile, those with a trade or apprenticeship education or those who used recreational drugs," it said.
"Also, there was no significant change in high-risk drinking patterns after the first trimester for any sociodemographic group over the five years."
It found that low-level alcohol consumption (defined as between half a standard drink and two standard drinks on any occasion) was associated with older, more highly educated women, and those from higher-income households.
"Low-level alcohol consumption after the first trimester increased with increasing age, education and income, and high-risk consumption after the first trimester was more common in single women and women who did not complete school," it said.
The researchers said consuming alcohol during pregnancy may contribute to birth defects, growth and developmental abnormalities, and foetal mortality.
Australia's National Health and Medical Research Council has since 2009 recommended that the safest option for pregnant women was zero alcohol consumption.
Alcohol abuse is considered a serious problem in Australia, where about one in five people drink alcohol at a level that puts them at risk of harm or injury over their lifetime, according to the National Drug and Alcohol Research Centre.