The urban environment during pregnancy influences the risk of wheezing and respiratory infections in early childhood

Environmental conditions during pregnancy can affect the respiratory health of young children. This is the main conclusion of a study conducted by the Barcelona Institute for Global Health (ISGlobal), a centre supported by ”la Caixa” Foundation. The results have been published in the journal Environment International.

Cities could be regarded as “allies” for health: they concentrate healthcare and education services and generate economic opportunities that can improve quality of life. However, urban living also exposes people to harmful environmental factors and less healthy patterns of behaviour, especially in car-dominated environments.

To understand this balance, researchers use the concept of the “urban exposome”. This term encompasses all the exposures a person encounters in a city, from physical and chemical factors such as air pollution, noise and temperature, to social aspects linked to lifestyle. The combination of these factors can influence several dimensions of child health, including respiratory function.

The urban exposome during pregnancy

However, it’s not just how much we are exposed that matters, but also when. Pregnancy is a particularly sensitive period. Any change in the maternal environment can affect foetal development, including lung maturation and immune system function.

“Our aim was to assess the association between the full set of urban exposures during pregnancy — air quality, noise, temperature, humidity, the presence of natural spaces, socioeconomic status and lifestyle — and wheezing and respiratory infections in childhood,” explains Robin Mzati Sinsamala, a doctoral researcher at the Department of Global Public Health and Primary Care of the University of Bergen, Norway, and first author of the study.

To do this, the team analysed data from 1,032 mothers and their children participating in the Barcelona Life Study Cohort (BiSC), followed between 2018 and 2021. In total, 44 urban exposome factors were evaluated using environmental monitoring systems, geospatial analyses and questionnaires. Wheezing episodes and respiratory infections in the infants were documented at 2, 6, 12 and 18 months of life.

Effects in the earliest stages of life

The results indicated that associations between the prenatal urban exposome and the onset of respiratory problems were strongest between 2 and 12 months and were weaker or not evident at 18 months, a pattern compatible with a more acute rather than persistent relationship between prenatal exposures and early respiratory health.

Not everything in urban environments is harmful: Access to green spaces during pregnancy and other beneficial factors

The most consistent protective factor was the presence of green spaces smaller than 5,000 m² near the mother’s home. These areas are typically more accessible and frequently used, and are known to help reduce stress, encourage physical activity, support social interaction and increase exposure to microbial agents. However, greater exposure to allergens such as pollen may also lead to adverse effects.

Engaging in light physical activity and having pets during pregnancy were also associated with a lower risk of wheezing and respiratory infections in children. Physical activity during pregnancy is linked to several benefits, including the formation of new blood vessels in the placenta. The potential benefits of having pets may be explained by the hygiene hypothesis: greater microbial diversity in early life may help modulate the immune system.

In addition, maternal secondary and university education was consistently associated with a lower risk of wheezing and respiratory infections.

The role of air pollution, environmental noise and temperature

On the other hand, exposure to nitrogen dioxide (NO₂), fine particulate matter (PM2.5), environmental noise and high outdoor temperatures during pregnancy was linked to a higher risk of respiratory problems in early childhood.

Although the mother's high level of education had been considered a protective factor, when studying the neighbourhood's socioeconomic indicators (such as a higher average income or a higher proportion of the population with higher education), these were associated with a higher probability of respiratory problems in childhood. The research team pointed out that in cities such as Barcelona, these ‘better-off’ areas are often located in busy central zones, making it difficult to determine whether the increased risk is due to the neighbourhood’s socioeconomic profile or to the associated air pollution and noise.

“Our results provide valuable insights that could inform the development of more effective public health interventions and policies, ultimately leading to a greater impact on population health,” concludes Payam Dadvand, coordinator of the BiSC cohort and researcher at ISGlobal.

Reference

Sinsamala, R. M., Anguita-Ruiz, A., Basagaña, X., Foraster, M., Gascon, M., Llurba, E., Luo, C., Nieuwenhuijsen, M. J., Persavento, C., Rivas, I., Zhao, Y., Gómez-Roig, M. D., Sunyer, J., Marcon, A., Johannessen, A., & Dadvand, P. (2025). Holistic evaluation of the impact of pregnancy urban exposome on infant wheezing and chest infections: an outcome-wide approach. Environment International, 205(109900), 109900. https://doi.org/10.1016/j.envint.2025.109900