Mom’s Exposure to Dirty Air in Pregnancy Could Harm a Toddler’s Development

A mother-to-be’s exposure to air pollution during pregnancy may have a lasting impact on her baby’s brain development, new research indicates.

Toddlers scored lower on assessments for thinking, motor and language skills when their mothers had more exposure to pollutants during pregnancy, according to researchers at the University of Colorado Boulder.

“Our findings suggest that pollution exposure, particularly during mid-to-late pregnancy, may negatively impact neurodevelopment in early life,” co-author Tanya Alderete, an assistant professor of integrative physiology, said in a university news release.

To study this, the researchers followed 161 healthy, Hispanic mother-infant pairs who lived in Southern California and were enrolled in the Mother’s Milk Study.

The moms provided information about where they had lived. This made it possible for researchers to calculate their exposure to pollutants from roadside traffic, industry, wildfire smoke and other sources using data from the U.S. Environmental Protection Agency.

The researchers assessed the children of these mothers for thinking (“cognitive”), motor and language skills at age 2 years. The team found that the toddlers who were exposed prenatally to more inhalable particulate matter (PM 10 and PM 2.5) scored significantly lower on cognitive tests. (Cognitive tests assess abilities such as problem-solving).

About 16% of the children had a composite cognitive score that indicated impairment. If all participants had been exposed to as much pollution as the 75th percentile, the researchers said, the prevalence of cognitive impairment at age 2 would be 22%.

When the exposures happened in mid-to-late pregnancy, these were particularly detrimental, said study co-author Zach Morgan, who earned a master’s degree in integrative physiology last year.

“The brain develops differently at different stages of pregnancy, and when you have a disruption at a critical window, that can affect the trajectory of that development,” Morgan said.

During mid-to-late pregnancy, key brain circuits form to support sensory, communication and motor systems, he added.

Inhaled pollutants may directly contact the fetus, according to past research. This can cause systemic inflammation and oxidative stress.

Past studies in older children have found associations between prenatal exposure to pollutants and reductions in white matter, cortex thickness and blood flow in the brain. This has also been associated with lower IQ scores.

About 90% of the world’s population is exposed to particulate matter levels exceeding recommended levels, Alderete said. Poor people and minorities are often subjected to greater levels of this type of pollution.

“Our findings highlight the importance of addressing the impact of pollution on disadvantaged communities and point to additional steps all families can take to protect their health,” Alderete said.

This exposure is not a guarantee that the child will have lasting cognitive deficits, she cautioned.

Alderete suggested that pregnant women can limit their risks by avoiding outdoor exercise on high pollution days, investing in an air filtration system inside the home and staying away from secondhand smoke.

The findings were published online Jan. 24 in the journal Environmental Health.

More information

The U.S. National Institute of Environmental Health Sciences has more on pollution and health.

SOURCE: University of Colorado Boulder, news release, Jan. 24, 2023