Prenatal Air Pollution Exposure May Influence Childhood Obesity Risk

Environmental factors such as air pollutants may contribute to childhood obesity risk, according to a study published in the journal Environmental International.1 The study identified a correlation between prenatal exposure to air pollutants—specifically, fine particulate matter with an aerodynamic diameter smaller than 2.5 µm (PM2.5)—and obesity prevalence in children across numerous European countries.

A total of 37,111 prenatal and 33,860 postnatal mother-child pairs were included in the study, and there was an association between prenatal air pollutant exposure and obesity in childhood. | Image credit: Victor Moussa - stock.adobe.com

Nearly 56% of the world’s population live in more polluted or urban areas, the study authors noted. Signs of exposure to air pollution include inflammation, decreased glucose utilization in skeletal muscles, endocrine system disruption, respiratory disease and decreased lung function, changes in basal metabolism, and appetite control of the central nervous system. Furthermore, PM2.5 is responsible for 4.2 million deaths worldwide, accounting for 7.6% of global deaths per year, and was the fifth leading risk factor for death in 2015.2

"There are critical windows of exposure to air pollution, including pregnancy and birth to 1 year of age, which are associated with development disorders, cancer, obesity, and other conditions in childhood," the study authors wrote.1 "Thus, it is possible that exposure to air pollutants during these periods may also have disproportionate impacts on child growth and adiposity. However, evidence is inconsistent."

The researchers created air pollution exposure estimates using data from 10 European birth cohorts, including continuous BMI (zBMI) scores stratified by ages 0 to 2 years, 2 to 5 years, 5 to 9 years, and 9 to 12 years. The cohorts varied by location and proximity to high deprivation areas with increased air pollutants. A total of 37,111 prenatal and 33,860 postnatal mother-child pairs were included in the study.

The prevalence of overweight/obesity ranged from 12.3% to 40.5% between cohorts at 0 to 2 years, 16.7% to 35.3% at 2 to 5 years, 12.5% to 40.7% at 5 to 9 years, and 10.7% to 43.8% at 9 to 12 years. Exposure to PM2.5 during pregnancy was associated with a 23% (95%CI, 1.05-1.37) higher overweight/obesity risk across childhood and higher zBMI and overweight/obesity risk at 9 to 12 years. Overall, increased prenatal exposure to PM2.5 was associated with an increased risk of overweight/obesity (OR, 1.23; 95% CI, 1.01-1.51).

“However, this age-specific analysis was based on less cohorts than the repeated outcome analysis due to less cohorts having data in this age group, and this result needs to be interpreted with caution,” the authors wrote.

The study did not find any associations between postnatal air pollution exposure and childhood zBMI and obesity. Previous literature has been inconsistent in providing statistically significant data associating postnatal air pollution exposure to above-average child BMI, the authors noted. There is little to no concrete evidence between NO2 and child obesity, and the evidence for PM2.5 is weak.

Exposure to pollutants or certain environmental factors during the developmental windows of pregnancy and birth to 1 year of age is associated with an increased risk of obesity and early adiposity. However, further study is required to determine the critical time window for potential effects of air pollution on childhood obesity. Prenatal exposure to air pollutants may impact child growth and adiposity and can be linked to atypical BMI growth patterns in early development.

“Overall, this large-scale meta-analysis suggests that prenatal PM2.5 exposure may be associated with adverse childhood obesity outcomes but provides no evidence to support an effect of postnatal air pollution exposure, although cohort-specific associations were observed,” the authors concluded.

References

1. Warkentin S, Fossati S, Marquez S, et al. Ambient air pollution and childhood obesity from infancy to late childhood: An individual participant data meta-analysis of 10 European birth cohorts. Environ Int. 2025; 200:109527. doi:10.1016/j.envint.2025.109527

2. Luo C, Wei T, Jiang W, et al. The association between air pollution and obesity: An umbrella review of meta-analyses and systematic reviews. BMC Public Health. 2024;24(1).doi:10.1186/s12889-024-19370-4