Pregnant women exposed to even low levels of air pollution during pregnancy face an increased risk of lower birth-weight babies, a study suggests.

The research report that was published in the Lancet Respiratory Medicine Journal finds that the exposure to common air pollutants and traffic during pregnancy significantly increases the risk of restricted foetal growth and have a higher risk of health problems and death of babies.

The study was done in 12 European countries involving over 74,000 women.

The researchers found that for every increase of five micrograms per cubic metre in exposure to fine particulate matter discharged by cars and industrial houses during a woman's pregnancy, the risk of low birth-weight rises by 18 percent.

According to the study, all air pollutants, particularly fine particulate matter and traffic fumes increased the risk of term low birth-weight and reduced average head circumference at birth, after accounting for other factors like maternal smoking, age, weight, and education.

“Our findings suggest that a substantial proportion of cases of low birth-weight at term could be prevented in Europe if urban air pollution, particularly fine particulate matter, was reduced”, lead author of the study Marie Pedersen of the Centre for Research in Environmental Epidemiology in Barcelona said.

“The widespread exposure of pregnant women worldwide to urban ambient air pollution at similar or even higher concentrations than those assessed in our study provides a clear message to policy-makers to improve the quality of the air we all share,” Pedersen added.