A new study, led by the Barcelona Institute for Global Health, has found that exposure to air pollution during pregnancy may influence how a baby’s brain develops before birth.
Researchers followed more than 1,000 pregnant women in Barcelona between 2018 and 2021. All participants were in the early stages of pregnancy and expecting single babies without major health issues. Using detailed brain scans later in pregnancy, scientists examined how the babies’ brains were growing in the womb.
The study focused on nitrogen dioxide (NO₂), PM2.5 and black carbon, with the team looking at the air pollution levels at home, at the mothers’ workplaces and during travel. These exposures were calculated using a geolocation app installed on the participants’ mobile phones.
Among the 754 pregnancies which were studied in depth, researchers found that babies exposed to higher levels of these pollutants showed some differences in brain development. For example, they had wider spaces in parts of the brain (such as the ventricles and cisterna magna) and changes in brain structures like the cerebellar vermis, which helps with movement and coordination.
Black carbon, was also linked to a shallower Sylvian fissure, a brain fold that plays a role in language and communication.
Payam Dadvand, ISGlobal researcher and a senior author of the study. said: ‘During mid to late gestation, the foetal brain enters a key phase of its development, making it particularly vulnerable to external factors such as pollution.’
While not all brain areas were affected, the findings suggest that mid-to-late pregnancy may be a particularly sensitive time for foetal brain development when it comes to air pollution.
Although all the measurements of the participants’ brain structures are within what would be considered a normal range, Laura Gómez-Herrera, ISGlobal researcher and co-lead author of the study observes: ‘The point is that these differences, although small at the individual level, are indeed relevant from a population perspective, as they inform us about how pollution affects the foetal brain and its vulnerability to environmental exposures.’
Jordi Sunyer, a senior author of the study: ‘At this stage, we can only report having observed differences in the brains of foetuses with higher exposure to pollution compared to those with lower exposure. Additional research is needed to determine whether these effects are reversible after birth or if they persist, and whether they have any implications for neurodevelopmental outcomes in later stages.’
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