Exposure to air pollution during mid-to-late pregnancy interferes with fetal neurodevelopment.

Exposure to air pollution during mid-to-late pregnancy interferes with fetal neurodevelopment, a new study shows. Children whose mothers were exposed to high levels of air pollution scored roughly three points lower on cognitive tests than children exposed to lower levels.

The study involved 161 mother-child pairs living in Southern California, an area known for its high air pollution levels. The researchers gauged the mothers' exposure to particulate matter (a mixture of solid particles and liquid droplets that may have neurotoxic properties) during their pregnancies. When the children reached the age of two years, they underwent tests to assess their neurodevelopment.

The researchers found that children who were exposed to particulate matter in air pollution during pregnancy – especially during the second and third trimesters – had lower composite cognitive scores than children exposed to lower levels. They also performed worse on measures of fine and gross motor skills, language, and expressive communication.

These findings suggest that fetal exposure to particulate matter in air pollution during the second and third trimesters of pregnancy impairs cognitive performance later in life. These trimesters correspond with periods during which critical neurodevelopmental processes occur, such as myelination, neuronal migration, synaptogenesis, and neurogenesis.

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