Exposure to high levels of certain air pollutants during pregnancy could increase the risk of abnormal fetal growth according to a new study from Yale School of Public Health (YSPH). Researchers say the study is the first of its kind to be carried out in areas with very high air pollution levels.

Many recent studies have already suggested that air pollution poses a serious threat to health, finding associations between exposure to pollutants and an increased risk of conditions such as heart disease, asthma and male infertility. However, according to the team behind the new study there is a lack of research looking into the effect of pollution on fetal growth. 

To test their hypothesis that high levels of PM10 during pregnancy increases the risk of abnormal fetal growth, the researchers analyzed data from more than 8,000 women in Lanzhou, China between 2010 to 2012.

Particulate matter (PM) are particles found in the air that includes dust, dirt, smoke and liquid droplets. PM10 particles are less than 10 microns or 10 millionths of a meter across, which is several times thinner than a human hair.

In collaboration with researchers from the Gansu Provincial Maternity and Child Care Hospital, the team collected the daily average concentration for PM10 from the government monitoring stations in Lanzhou, and used ultrasound to measure four fetal growth parameters during pregnancy.

The results consistently showed a positive association between higher levels of exposure to pollutants and a higher risk of fetal head circumference overgrowth.

Yawei Zhang, MD, associate professor at YSPH, commented on the findings saying that the results now need to be confirmed by other studies which look at different populations.

He also added that it is important to identify the specific pollutants that are responsible for increased risk of fetal overgrowth by investigating the different components of PM10.

"Our results have important public health implications and call for future studies to explore the underlying mechanisms and postnatal consequences to the findings," says Zhang. "We are going to replicate the findings in another birth cohort and will continue to identify individuals who are more susceptible to air pollution."

Zhang also added that women in the Lanzhou region may lower the risk of fetal overgrowth by choosing their inception time and reducing their outdoor activities during the days with high air pollution.