Published: 15-10-2013 00:00 | Updated: 15-02-2014 18:11

Air pollution causes lower birth weight

A new study shows that exposure to airborne pollutants during pregnancy, even at levels below the European Air Quality Directive, increases the risk of low birth weight. The study, which involves researchers from Karolinska Institutet's Institute of Environmental Medicine, is one of the largest of its kind and is reported in the latest issue of Lancet Respiratory Medicine.

Low birth weight, which is often defined as below 2.5 kg (5.5 lbs), is associated with several adverse health effects later in life, such as respiratory symptoms, impaired pulmonary function and cardiovascular diseases. The results of the study reveal a correlation between the risk of low birth weight and exposure to different kinds of airborne particles, especially PM 2.5, a kind of tiny particles created by traffic and industrial emissions. An increase in exposure by 5 micrograms per cubic metre corresponded with an 18 per cent increase in the risk of low birth weight. This relationship was also observed for levels of air pollution below the EU's Air Quality Directive.

Data was gathered for the study through the European Study of Cohorts for Air Pollution Effects (ESCAPE) project, and included 14 cohort studies from 12 European countries, giving a total of 74,000 births between 1994 and 2011. Sweden's contribution was the BAMSE birth cohort, which comprises babies born in Stockholm county between 1994 and 1996.

"The results are interesting from a public health perspective too, and the combined effects of air pollution on birth weight were of the same order of magnitude as for smoking during pregnancy," says Professor Göran Pershagen at the Institute of Environmental Medicine, who led the Swedish part of the study.

ESCAPE is coordinated from Utrecht University in the Netherlands and funded through the EU's Seventh Frame Programme (FP7). The BAMSE project was set up to investigate risk factors for asthma and allergies in children, and is run by the Institute of Environmental Medicine at Karolinska Institutet together with the Centre for Occupational and Environmental Medicine at the Stockholm County Council. BAMSE has followed over 4,000 babies born between 1994 and 1996.


Ambient air pollution and low birthweight: a European cohort study (ESCAPE).
Pedersen M, Giorgis-Allemand L, Bernard C, Aguilera I, Andersen A, Ballester F, et al
Lancet Respir Med 2013 Nov;1(9):695-704