Prenatal and early-life pollution exposures may influence childhood blood pressure patterns, ECHO study finds 

A child’s blood pressure may be influenced by exposure to air pollution before and shortly after birth, according to a new study from the NIH-funded Environmental influences on Child Health Outcomes (ECHO) Program. The study focused on fine particulate matter (PM_2.5) and nitrogen dioxide (NO₂), common pollutants from vehicles, power plants, and other industrial sources. 

High blood pressure in children is becoming more common worldwide and can lead to long-term health problems, including heart disease and impaired kidney function. Over the past two decades, childhood hypertension has increased by nearly 80 percent, particularly in countries with higher obesity rates, such as the United States. Because the roots of adult hypertension often begin in childhood, ECHO researchers examined whether early exposure to outdoor air pollution may influence blood pressure in children. 

Air pollutants such as fine particulate matter (PM_2.5) and nitrogen dioxide (NO₂) are known contributors to cardiovascular disease in adults, but their effects on children’s blood pressure are less well understood. Previous studies have produced mixed results and were often limited to single locations. This ECHO study leveraged data from multiple cohort sites across the United States to better clarify these associations. 

Researchers analyzed data from 4,863 children ages 5 to 12 from 20 ECHO Cohort Study Sites. They estimated outdoor air pollution exposure at participants’ home addresses during each trimester of pregnancy, across the full pregnancy, and during the child’s first two years of life. Children’s blood pressure was measured during study visits and compared with typical values for children of the same age, sex, and height. Blood pressure was considered high if it fell within the top 10 percent of these values. 

Key Findings 

• PM_2.5 exposure and higher blood pressure: Children who were exposed to higher levels of PM_2.5 before and after birth had higher blood pressure on average between ages 5 and 12. 

• Early pregnancy as a sensitive period: Higher PM_2.5 exposure during the first trimester was associated with a more pronounced systolic blood pressure and a greater likelihood of high blood pressure in childhood, indicating that early pregnancy may be a particularly sensitive period. 

• Unexpected findings for NO₂: Higher maternal exposure to NO₂ during pregnancy was associated with slightly lower blood pressure in children. This association was strongest during mid- to late pregnancy, particularly in the second trimester, and was not associated with an increased risk of high blood pressure. 

• Timing matters: The results suggest that the timing of exposure to pollution during pregnancy may be important for understanding its impact on children’s cardiovascular health. 

“These findings add to growing evidence that early-life exposure to fine particulate air pollution may affect children’s cardiometabolic health, even at relatively low levels,” said study author Yu Ni, PhD, of San Diego State University. “The unexpected findings related to nitrogen dioxide suggest that more research is needed to understand how this type of air pollution may affect children’s developing bodies, as well as whether other environmental factors could be playing a role, such as transportation noise.” 

This collaborative research was published in Environmental Research. 

About ECHO
The ECHO Cohort Consortium is a research program supported by the National Institutes of Health (NIH) with the mission to enhance the health of children for generations to come. ECHO Cohort investigators study the effects of a broad range of early environmental influences on child health and development. For more information, visit echochildren.org.