A new study by Rutgers University researchers found that children with higher prenatal exposure to fine particles from wildfire smoke were more likely to be later diagnosed with autism.
The study, published in JAMA Pediatrics, analyzed Medicaid health insurance records of nearly 900,000 pairs of mothers and children born between 2007 and 2014 across the United States. Researchers used modeled estimates of weekly wildfire smoke concentrations in the areas where each pregnant person lived.
For every incremental rise in air pollution, the risk of autism rose by 30%, the study found. The fine particles involved, known as PM 2.5, are 30 times smaller than the width of a human hair and are easily inhalable; they can settle deep in the lungs and enter the bloodstream.
Stefania Papatheodorou, an OB-GYN and epidemiologist at the Rutgers School of Public Health who led the study, said: “We already know that exposure to wildfire smoke is harmful. There is very little evidence on how exposure to wildfire smoke during pregnancy could affect neurodevelopment during childhood. That’s why we decided to combine these questions together and examine this association in a large database.”
Because the study was observational, it cannot establish that wildfire smoke causes autism, and Papatheodorou said additional studies are needed to confirm the association.
Papatheodorou encourages obstetricians to consider environmental hazards like wildfires and extreme heat when practicing routine prenatal care. She recommends pregnant people limit their time outdoors when air quality is poor and use home air purification systems. She noted that harmful particulate matter levels can be present even without visible smoke, and advised checking air quality on smartphones.
The study comes as scientists say climate change will cause more wildfires. New Jersey firefighters have recently battled an unseasonably high number of wildfires triggered by severe drought conditions. “The population disease burden is going to increase with the increased exposure to fires,” Papatheodorou said. “If people are aware of the health risks, they can take measures to protect themselves.”
Analysis
Why This Matters
- Wildfire smoke can travel great distances and affect communities far from the fires, as seen when Canadian wildfires caused smoky air over the Philadelphia region in 2023, closing schools and delaying flights.
- The study adds to growing evidence that air pollution during pregnancy can affect neurodevelopment, with implications for prenatal care guidance as wildfires increase due to climate change.
- Pregnant people may need to monitor air quality and limit outdoor exposure even when smoke is not visible.
Background
Wildfire smoke contains fine particulate matter (PM 2.5) that can penetrate deep into the lungs and enter the bloodstream, causing respiratory and cardiovascular problems. Climate change is expected to increase the frequency and intensity of wildfires in many regions, including the northeastern United States and Canada.
Key Perspectives
Stefania Papatheodorou (Rutgers School of Public Health, study lead): Says the study provides evidence that prenatal wildfire smoke exposure is associated with autism risk, and that pregnant people should check air quality and limit time outdoors when levels are harmful. She also notes the study is observational and cannot prove causation.
What to Watch
- Whether additional studies confirm the association and establish a causal link.
- Whether obstetricians begin incorporating wildfire smoke risk into routine prenatal care guidance.
- The frequency and severity of future wildfire seasons as climate change progresses.
Checked
12 claims in this story checked against 1 source: 12 supported.
Show each claim
- SupportedThe study found prenatal wildfire-smoke exposure may be associated with autism risk.WHYY: “A pregnant person’s exposure to wildfire smoke may increase their child’s risk of developing autism, according to a new Rutgers University study.”
- SupportedThe Rutgers-led study analyzed nearly 900,000 mother-child pairs.WHYY: “Researchers from Rutgers, the Harvard T.H. Chan School of Public Health, Emory University, Massachusetts General Hospital and other institutions analyzed Medicaid health insurance records of almost 900,000 pairs of mothers and children”
- SupportedThe study found a 30% increase in autism risk for every incremental rise in air pollution.WHYY: “For every incremental rise in air pollution, the risk of autism rose by 30%, according to the study.”
- SupportedThe risk was greater during the second and third trimesters.WHYY: “The risk was greater during second and third trimesters — though brain development continues throughout pregnancy.”
- SupportedChildren with higher prenatal exposure to fine particles from wildfire smoke were more likely to be later diagnosed with autism.WHYY: “The study, published in JAMA Pediatrics, found that children with higher prenatal exposure to fine particles from wildfire smoke were more likely to be later diagnosed with autism.”
- SupportedThe analyzed Medicaid records were for children born between 2007 and 2014 across the United States.WHYY: “analyzed Medicaid health insurance records of almost 900,000 pairs of mothers and children born between 2007 and 2014 across the U.S.”
- SupportedPapatheodorou said, “We already know that exposure to wildfire smoke is harmful.”WHYY: ““We already know that exposure to wildfire smoke is harmful,” said Stefania Papatheodorou”
- SupportedPapatheodorou said, “There is very little evidence on how exposure to wildfire smoke during pregnancy could affect neurodevelopment during childhood. That’s why we decided to combine these questions together and examine this association in a large database.”WHYY: ““There is very little evidence on how exposure to wildfire smoke during pregnancy could affect neurodevelopment during childhood. That’s why we decided to combine these questions together and examine this association in a large database.””
- SupportedThe fine particles known as PM 2.5 are 30 times smaller than the width of a human hair.WHYY: “These fine, tiny particles, known as PM 2.5, are 30 times smaller than the width of human hair, and are easily inhalable.”
- SupportedBecause the study was observational, it cannot establish that wildfire smoke causes autism, and additional studies are needed to confirm the association.WHYY: “Because the study was observational, it cannot establish that wildfire smoke causes autism and she said additional studies are needed to confirm the association.”
- SupportedPapatheodorou recommends that pregnant people limit time outdoors when air quality is poor and use home air purification systems.WHYY: “She recommends pregnant people limit their time outdoors when air quality is poor, and to use home air purification systems.”
- SupportedPapatheodorou said, “The population disease burden is going to increase with the increased exposure to fires.”WHYY: ““The population disease burden is going to increase with the increased exposure to fires. So, it is something that we need to pay a lot of attention to,” Papatheodorou said.”