The study analysed data from 754 mother-foetus pairs collected between 2018 and 2021. Using transvaginal neurosonography—a specialised ultrasound method that offers detailed views of the foetal brain—researchers examined brain structures during the third trimester
Maternal exposure to pollution during pregnancy—especially in the second and third trimesters—can lead to measurable changes in the brain structure of unborn babies, a new study published in The Lancet Planetary Health has found.
The research, led by experts from the Barcelona Institute for Global Health (ISGlobal), showed that pollutants such as nitrogen dioxide (NO₂), fine particulate matter (PM2.5), and black carbon were associated with specific structural changes in the foetal brain. These changes were linked to motor coordination issues and slower neurodevelopment.
“During mid to late gestation, the foetal brain enters a key developmental phase, making it particularly vulnerable to external factors like pollution,” said Payam Dadvand, researcher at ISGlobal. Clinicians Elisa Llurba and Lola Gómez-Roig, from Hospital de Sant Pau and BCNatal-Hospital Sant Joan de Déu respectively, added: “We are seeing compelling evidence that even in pregnancies that appear healthy, air pollution can subtly affect foetal brain development.”
The study analysed data from 754 mother-foetus pairs collected between 2018 and 2021. Using transvaginal neurosonography—a specialised ultrasound method that offers detailed views of the foetal brain—researchers examined brain structures during the third trimester.
The scans revealed increases in the volume of several cerebrospinal fluid-filled brain cavities. Specifically, they found enlargement of the lateral ventricles in each hemisphere and the cisterna magna at the brain’s base. There was also an increase in the width of the cerebellar vermis, the central part of the cerebellum, which is vital for balance and motor coordination.
The findings suggest these structural differences may point to less brain maturation in babies exposed to higher pollution levels.
“These differences, although small on an individual level, are significant from a population perspective,” said Laura Gómez-Herrera, researcher at ISGlobal. “They highlight the foetal brain’s vulnerability to environmental exposures and underscore the importance of reducing pollution.”
The researchers called for further studies to confirm these results and urged greater public awareness about the risks posed by pollution during pregnancy, not just within the medical community but across society at large.
