Wildfire smoke exposure during pregnancy linked to higher autism risk in children, study finds

A large-scale study by the American Medical Association's pediatrics division has found that exposure to wildfire smoke during pregnancy, particularly in the second and third trimesters, is associated with an increased risk of autism in children.

Autism rates in the United States have risen significantly in recent decades, raising public concern about factors that may contribute to its prevalence.

The new study included 893,212 mothers and children enrolled in Medicaid, the federal health program for low-income Americans, covering children born across the United States between 2007 and 2014.

Researchers analyzed weekly estimates of wildfire smoke concentrations for the mothers' residential zip codes, focusing on inhalable particles with a diameter of 2.5 micrometers or less.

They found that each 0.75 microgram per cubic meter increase in average fine particulate matter from wildfires during pregnancy was linked to a 30% higher risk of autism in children by age eight.

The study is observational and cannot prove whether or how wildfire smoke causes autism.