Exposure to air pollution can lead to changes in foetal brain structures

Exposure to air pollution affects foetal development. This is what has been shown for the first time in a study led by researchers at the Barcelona Institute for Global Health (ISGlobal) and involving the Hospital de la Santa Creu i Sant Pau and the BCNatal foetal medicine centre (Hospital Sant Joan de Déu, Hospital Clínic and the University of Barcelona). Specifically, they found that the most exposed foetuses showed changes in the size of some brain structures.

The study was conducted with the Barcelona Life Study Cohort (BISC) and involved 754 pregnant women between 2018 and 2021. The researchers analysed exposure to nitrogen dioxide (NO₂), 2.5-micron airborne particles (PM_2.5) and black carbon in three different microenvironments: the home, the workplace and during commuting. They collected activity data via a mobile app with geolocation.  Changes in foetal brain structures were detected using an ultrasound called transvaginal neurosonography, performed on women in the third trimester of pregnancy.

The research team found that increased exposure to contaminants in either microenvironment was associated with increased volume of the lateral ventricles, enlargement of the cisterna magna and increased width of the cerebellar vermis. Both the lateral ventricles and the cisterna magna contain cerebrospinal fluid, while the cerebellar vermis is involved in balance and motor coordination. In addition, they detected a link between back carbon exposure and a reduced depth of the lateral sulcus that might suggest reduced brain maturation. All the changes were most significant during the second and third trimester of pregnancy, when ‘the foetal brain enters a key phase of its development, making it particularly vulnerable to external factors’, says Payam Dadvand (ISGlobal), senior author of the paper.

It should be noted that, despite the changes, all the brain structures analysed are within normal limits and do not necessarily lead to the development of pathologies. Furthermore, the study has not analysed the effects of these brain changes in the long term.

However, Laura Gómez-Herrera (ISGlobal), co-lead author of the article, warns that ‘the differences are relevant from a population perspective, as they inform us about how pollution affects the foetal brain and its vulnerability to environmental exposures’.  Co-lead author Yu Zhao (ISGlobal) adds that ‘the findings strengthen the evidence for the need to reduce pregnant women’s exposure to air pollution, especially in urban settings’.