Pollution from heavy traffic affects the size of an unborn baby

According to Australian researchers the pollution caused by heavy traffic affects the size of an unborn baby.

The researchers from Queensland University in Brisbane say their study sends out a warning to all to pregnant women who live in urban areas with a high volume of traffic.

Over the last decade there has been growing evidence that air pollution during pregnancy affects the growth of a fetus but the researchers say their study is the first to show the effect of air pollution before birth.

The study found that mums-to-be who live in heavy traffic suburbs are carrying smaller foetuses than those from "cleaner" areas and the pollution affects the fetus at a vital and vulnerable stage of development.

Dr. Adrian Barnett one of the research team says the study demonstrates that air pollution causes changes very early on, when the brain and organs are still developing.

Dr. Barnett suggests on this basis, women should think carefully about reducing their exposure if they are pregnant.

For the study the researchers compared the foetus sizes of more than 15,000 ultrasound scans to air pollution levels in different postcodes within a 14-kilometre radius of downtown Brisbane at between 13 and 26 weeks of development.

Dr. Barnett says the study found that mothers with a higher exposure to air pollution had foetuses that were, on average, smaller in terms of abdominal circumference, head circumference and femur length.

Most air pollution in cities is caused by traffic, in particular by the sulphur dioxide found in diesel emissions and the research revealed that if the pollution levels were high the size of the foetus decreased significantly.

Dr. Barnett says research has shown that bigger babies were healthier in childhood and adulthood, and foetus size during pregnancy was important because birth weight is a major predictor of later health.

Barnett says bigger babies have been shown to have higher IQs in childhood and lower risk of cardiovascular disease in adulthood.

Dr. Barnett says while Australian cities have relatively low air pollution levels compared with other cities, the outdoor lifestyle and home design maximises airflow and increases exposure; so although the actual levels of pollution are low exposure to pollution is relatively high and a particular problem for people who live near major roads.

The researchers plan to conduct further research and collect more data from individual mothers to be clear about the effects of air pollution on foetal development but they warn mothers-to-be to try to reduce their exposure to such air pollution.

The study is published in the international journal Environmental Health Perspectives.