and the University of South Australia studied almost 100,000 live single births in Montreal between 1997 to 2001 in which mothers lived within 200 metres of a highway.
Mothers residing within 200 metres of a highway were found to have 14 per cent increased odds of pre-term birth and 17 per cent increased odds of low birth weight, compared with mothers who did not live close to a highway.
But they also found that the percentage of affluent mothers in this group delivering low birth-weight babies was far higher.
"Among affluent mothers who live within 200 metres of a highway, the odds of delivering an infant with low birth weight increase by 81 per cent, while their odds of delivering a pre-term baby increase by 58 per cent compared to mothers who don't live anywhere close to expressways," said Dr. Melissa Genereux, one of the study's authors, in a release.
Women who were wealthier and lived in higher-income neighbourhoods were also found more likely to deliver pre-term, low weight or smaller babies.
"Advantaged mothers may be more susceptible to environmental hazards because they have been protected from other hazards," reads the study. "These mothers may be particularly susceptible to exposure to air pollution during pregnancy, which is hypothesized to interfere directly with intrauterine growth via pollutant absorption and placental exchange, or indirectly by increasing maternal susceptibility to infection or impairing maternal respiratory function."
Another theory put forth by the researchers is that living close to a highway may become a chronic stressor, as it generates noise pollution, and thus alters the mother's emotional state and the well-being of her unborn child.
The study, published in the August issue of the Journal of Epidemiology and Community Health, was conducted as part of a project that monitors health in the province of Quebec.