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Health

Breathing polluted air during pregnancy increases risk of child obesity

A study in eight countries points to airborne micro-particulate matter from traffic, heating and industrial burning as the main trigger

Monday, 30 June 2025, 12:07

Breathing air with high concentration of pollution during pregnancy increases the risk of childhood obesity. A study led by the Barcelona Institute for Global Health (ISGlobal), conducted in eight countries, has found that suspended microparticles (PM2.5) are the main risk factor.

PM2.5 are a common component of air pollution in cities and metropolitan areas generated by vehicle combustion (especially diesel) and other activities in which fossil fuels are burned, such as heating or certain industrial processes.

The study has analysed the links between daily exposure to the main elements of air pollution during pregnancy and subsequent childhood obesity before the age of 13 in more than 30,000 families from eight countries, including Spain.

To carry out the study, the researchers determined the concentrations of PM2.5 and nitrogen dioxide (NO3) - the toxic gas released by exhaust pipes - in the residential area of each of the participating families. The study lasted from the beginning of the pregnancy until the child was 12 years old, involving continuous clinical monitoring of the children. Their height and weight were monitored through the years to see the evolution of their body mass index (BMI).

The main finding of the study is that, when mothers breathed air with high levels of particulate matter during pregnancy, the risk of having overweight or obese children increased by 23%. The overweight stage of childhood occurred mainly when the child was between 9 and 12 years old. However, there were no notable increases in the risk of obesity either among children living in areas with high PM2.5 (but not their mothers when they were pregnant) or among pregnant women or their children due to NO3 exposure. In short, "the results indicate that the gestational period may represent a particularly vulnerable window for childhood obesity risk", says Sarah Warkentin, ISGlobal researcher and first author of the study.

Possible explanations

"The biological mechanisms that may explain the relationship between air pollution exposure and weight gain in children are not yet fully understood. In previous studies, exposure to pollution during pregnancy has been linked to reduced foetal growth and low birth weight. This may be due to oxidative stress, inflammation, problems with placental development or hormonal disruptions. These same processes may also affect growth and increase the risk of obesity during childhood, as demonstrated in animal studies," says Martine Vrijheid, director of ISGlobal's lifelong environment and health programme and senior author of the study.

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surinenglish Breathing polluted air during pregnancy increases risk of child obesity

Breathing polluted air during pregnancy increases risk of child obesity