Over the study period, there were about 2500 reported cases of infertility. Women who lived close to a major roadway within less than 200m were 11% more likely to experience this problem than women who lived farther from a highway, the study found.
Though the risk is slight, but even the slightly increased risk can present a big global public health problem, said Mark Nieuwenhuijsen, a researcher at the Centre for Research in Environmental Epidemiology and the Barcelona Institute for Global Health.
"For an individual woman the results might not be that important because the risk of infertility increases only slightly, but for society as a whole it is important because so many women are exposed to air pollution," Nieuwenhuijsen added.
The study was one of the first of its kind to follow so many women over such a long period of time and more research is needed before medical recommendations based on the results can be made, Mahalingaiah said.
Even so, the findings add to a growing body of evidence suggesting that pollution can hinder conception efforts, said Sajal Gupta, a researcher at Cleveland Clinic, in Ohio, who was not involved in the study.
"Couples suffering from infertility need to be careful, especially if they live in an area in which there is high particulate pollution," Gupta said.
Infertility is only one of many health problems tied to air pollution, noted Christopher Somers, a biology researcher at the University of Regina, in Canada.