Researchers from the University of Western Australia (UWA) and the Telethon Institute of Child Health Research found that mothers living in suburbs with average levels of vehicle emissions gave birth to children weighing 58g below their expected weight.
The decrease in birth weight of suburban babies was found to be about half the average weight reduction of a baby whose mother smoked throughout the pregnancy.
The study was based on 1800 pregnant women and their babies in a range of different suburban environments across Perth, with researchers measuring the levels of carbon monoxide around the homes of the pregnant women.
UWA epidemiologist Gavin Pereira told The West Australian the results surprised the researchers.
"I didn't really expect to see any effect, so it was pretty surprising, although some international studies have found some associations," Mr Pereira said."It was more the extent of the effect, because we would have expected it to be almost negligible because Perth is not really a polluted city."
He said the investigation highlighted the need to look more closely at the distance between houses and major roads, and to focus on reducing vehicle emissions and increasing public transport use.
"We need to do a lot more work on this because as researchers we can't say the exact distance we should be building away from these roads.”