A mother's exposure to air pollution during pregnancy can increase asthma risk in her adult offspring, according to a new mouse study published at the ATS 2025 International Conference. Researchers also found that offspring had lasting epigenetic changes affecting their lungs and immune response.
While previous research has suggested that maternal air pollution exposure may increase childhood asthma risk, the study provides new insights into how epigenetic mechanisms may be driving this effect. It also indicates that, even if an individual is never directly exposed to air pollution themselves, their health can still be impacted if their mother was exposed during pregnancy.
This highlights the importance of protecting pregnant women from air pollution, as its effects can persist across generations."
Razia Zakarya, PhD, Wendy McCormick Research Fellow, University of Technology Sydney, and researcher at the Epigenetics of Chronic Disease Group, Woolcock Institute of Medical Research
The link between air pollution and asthma prevalence, severity, and hospitalizations is well established. However, there is a need to better understand the molecular pathways driving this connection, so they can be targeted for prevention and treatment. In particular, the "molecular memory" involved in prenatal exposure is not well understood, Dr. Zakarya noted.
For the new paper, researchers studied the effects of maternal air pollution in mice. In the first stage, they exposed one group of pregnant mice to air pollution particulates, and another group to harmless saline. They then separated their offspring into groups with and without asthma.
Adult mice whose mothers had been exposed to air pollution while pregnant had stronger airway constriction in response to allergens, making their asthma symptoms worse than their counterparts.
The team also found that thousands of genes in the lungs of these offspring were expressed differently than those from unexposed mothers. In addition, they found maternal air pollution exposure altered the offspring's DNA methylation patterns - an epigenetic modification that controls gene activity.
"This suggests an epigenetic 'memory effect' of prenatal air pollution exposure that persists into adulthood, affecting the way genes related to lung function and immune response are regulated," Dr. Zakarya said.
Notably, the levels of air pollution tested in the study meet WHO air quality guidelines for "safe," she said, suggesting that guidelines may need to be revisited.
Next, the team plans to follow up on the study with future research focusing on whether similar epigenetic changes occur in human populations. They also hope to study how these changes might be reversed or mitigated.
Understanding the psychological toll of asthma or allergies