Exposure to air pollution during pregnancy may increase babies’ obesity risk

Poor air quality may contribute at least in part to the nation’s obesity epidemic.


A new study has suggested how much of an environmental burden one carries. Past studies have indicated that women who smoke or are chronically exposed to air pollution tend to have smaller birth weight babies. The period, either during pregnancy or shortly after birth, is a critical window of development.

Adverse exposure during this period can lead an infant to have several problems later in life. In a new study, scientists from the University of Colorado Boulder aimed to determine how specific pollutants impact a baby’s growth trajectory.

For this, they 123 mother-infant pairs from the Mother’s Milk Study. About one-third were of normal weight pre-pregnancy, one-third overweight, and one-third obese. Later, scientists used the data from the U.S. Environmental Protection Agency’s Air Quality System.

The record helps them identify participant’s prenatal exposure to four classes of pollutants: PM2.5 and PM10 (inhalable particles from factories, cars, and construction sites), nitrogen dioxide, and ozone. Then they followed the babies, periodically measuring their weight and height and how much fat they carried and where.

Lead author William Patterson, a doctoral student, said, “We found that greater exposure to prenatal ambient air pollution was associated with greater changes in weight and adiposity, or body fatness, in the first six months of life.”

Scientists also found different impacts of pollutants in males and females. For instance, exposure to a combination of ozone and nitrogen dioxide in utero was associated with faster growth around the waist in females. In males, it was associated with slower growth in length and greater fat accumulation around the midsection. In adults, excess fat around the midsection has been linked to heart disease and diabetes.

Pollutants have also been shown to impact gene expression in infants, potentially having life-long impacts that could transcend generations.

Authors noted, “because the study included only Hispanic mothers, a larger trial is necessary to confirm results apply to other populations.”

Meantime, it is recommended that pregnant women minimize their exposure to air pollution by closing windows on high ozone days, not exercising outdoors at times of high air pollution, and steering clear of activities alongside busy roadways.

Journal Reference:

  1. Patterson, W.B., Glasson, J., Naik, N. et al. Prenatal exposure to ambient air pollutants and early infant growth and adiposity in the Southern California Mother’s Milk Study. Environ Health 20, 67 (2021). DOI: 10.1186/s12940-021-00753-8
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