A study of more than 200,000 mother-infant couples found that days of exposure to wildfire smoke late in pregnancy may slightly increase the risk of autism, highlighting a critical time to protect pregnant women.
study: Prenatal wildfire exposure and childhood autism. Image credit: Lumppini/Shutterstock.com
Prenatal exposure to wildfires and emitted particulate matter (afternoonAccording to a study published in ), a child’s risk of autism may increase during the third trimester. environmental science and technology.
Widespread prenatal exposure to wildfire smoke
The environmental and health risks from wildfires are increasing across the United States, as forest and grassland fires are rapidly spreading to more areas, and the smoke produced by these fires is spreading across much of the country.
Wildfires are caused by particulate matter (PM2.5), respirable air pollutants with a diameter of 2.5 micrometers or less. Exposure to these pollutants is associated with serious health risks, including respiratory disease, cardiovascular disease, and premature death.
Prenatal, pregnancy, exposure to PM2.5 It is thought to be associated with an increased risk of neurodevelopmental disorders in children. PM2.5 Energy from a variety of sources, including tailpipe exhaust and home heating, has been shown to increase the risk of autism in children.
wildfire PM2.5 Contains high levels of carbonaceous compounds such as levoglucosan. PAHcompared to metal, PM2.5 From other sources. Exposure to these toxic components of wildfires afternoon It is thought to be associated with decreased gestational age and birth weight, and increased risk of cognitive impairment in adulthood.
Given the significant health effects of wildfire smoke, the current study was designed to investigate whether children are exposed to wildfire smoke products before birth. PM2.5 Children are at increased risk of developing autism.
Measurement of smoke days, intensity and exposure waves
The study included 204,374 mother-infant pairs from a large pregnancy cohort at the Kaiser Permanente Southern California Health System. The children were followed for five years after birth for autism screening.
average wildfire PM2.5 Exposure concentrations, smoke exposure days, and number of smoke exposure waves were calculated throughout pregnancy and within each gestational period. A wildfire “wave” was defined as a multi-day smoke event consisting of two or more consecutive days, or three or more consecutive days, in which wildfire-specific PM2.5 concentrations exceeded predefined thresholds of 0, 3, or 5 μg/m, combining both duration and intensity of exposure.
Days of smoke exposure during the third trimester is associated with autism risk
The study found that about 60% of mother-child pairs were exposed to wildfires. afternoon More than 5 days during pregnancy. The median number of days of exposure was 8 days, with a mean of approximately 9.6 days, indicating a low frequency of exposure.
A separate analysis of mother-infant pairs who did not change their address during pregnancy (non-movers) revealed that they had higher exposure days and exposure concentrations.
The study identified 3,356 autism cases. Risk analysis revealed a significant association between increased exposure days during the third trimester and increased risk of developing autism in children by age 5 years. This risk was strongest among non-migrants. The magnitude of the estimated risk increase was modest.
Specifically, the study found prenatal exposure to wildfires. afternoon Exposure for 1 to 5 days during late pregnancy was associated with a significantly higher risk of autism compared to no exposure at all.
Regarding exposure to wildfire waves in combination of duration and intensity, the study found that exposure to wildfire waves of 2 and 3 days in the third trimester was significantly associated with increased risk of autism in the study population overall and among non-migrants. Some wave-based associations were also observed when assessing exposure during pregnancy. PM2.5 Threshold used.
Research supports targeted protection for pregnant women
The study revealed prenatal exposure to wildfire smoke. PM2.5 The third trimester of pregnancy is associated with an increased risk of autism in children. Of note, this study emphasizes that the frequency and duration of exposure are measured as days or waves rather than averages. PM2.5 Concentration alone was associated with autism risk.
In this study, we considered two specific things. PM2.5 Concentration thresholds for risk analysis are 3 and 5 μg/m3. However, no consistent dose-dependent increase in autism risk was observed. The researchers explained that this lack of a dose-response effect may be due to the small sample size and small number of participants with higher exposure thresholds.
Additionally, on days of high-intensity exposure, the possibility of evacuation, temporary relocation, or use of indoor particle filters remains. These factors may lead to misclassification of exposure and may partially explain why the association was stronger for non-movers than for movers.
This study identifies late pregnancy as a time when the risk of autism associated with wildfire exposure is higher. Late pregnancy is associated with rapid development of the fetal brain, characterized by increased connectivity and organization of neurons and rapid growth of gray matter. Acute exposure to wildfires afternoon It can affect these processes and increase the risk of neurodevelopmental disorders in children, including autism.
wildfire PM2.5 It contains high levels of carbonaceous components, which biologically contribute to the risk of autism based on previous toxicological and epidemiological evidence. more wildfires afternoon It is known to increase the risk of premature birth and may subsequently increase the risk of the child developing autism.
Wildfire-related anxiety and depression experienced by mothers during pregnancy may also increase the risk of autism in their children. Because maternal psychological stress was not directly measured, it may represent a potential mediating pathway or unmeasured factor influencing the observed association rather than a fully controlled confounder.
Future studies should consider other components of air pollution, such as maternal stress levels, household activities, climate temperature, and heavy metals, as potential confounders to better interpret wildfire impacts. afternoon About the risk of autism. As an observational cohort study, the results indicate an association rather than definitive causation, and the authors note that the results were not adjusted for multiple statistical tests.
Given these findings, the researchers advise public health officials to prioritize protecting pregnant women from wildfire smoke, especially in the third trimester.