EXPOSURE TO COMMON air pollutants and traffic during pregnancy significantly increases the risk of having a lower birthweight baby, according to a new study.

This increased risk of restricted foetal growth is present even at levels of pollution well below those stipulated in current European Union air-quality directives, the study, published in the Lancet Respiratory Medicine, found.

Researchers estimate that for every increase of 5 micrograms per cubic metre in exposure to fine particulate matter during pregnancy, found in traffic fumes or industrial air pollutants, for example, the risk of low birthweight at term raises by 18 per cent. Low birthweight babies are defined as those weighing less than five pounds, eight ounces.

“Our findings suggest that a substantial proportion of cases of low birthweight at term could be prevented in Europe if urban air pollution, particularly fine particulate matter, was reduced”, explained lead author Dr Marie Pedersen.

The study

Data from 14 cohort studies in 12 European countries was pooled, which over 74,000 mothers involved.

Air pollution concentrations of nitrogen oxides and particulate matter (PM 2.5; with a diameter of 2.5 micrometers or less) were estimated at the home addresses using land-use regression models. Traffic density on the nearest road and total traffic load on all major roads within 100m of the residence were also recorded.

All air pollutants, particularly fine particulate matter and traffic density increased the risk of term low birthweight and reduced average head circumference at birth, after accounting for other factors like maternal smoking, age, weight, and education.

Need to improve air quality

The researchers estimated that if levels of these particulates were reduced to the WHO annual average air quality guideline value, 22 per cent of cases of low birthweight among term deliveries could be prevented.

According to Pedersen, “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.”

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