WEDNESDAY, Jan. 21, 2026 (HealthDay News) -- Air pollution in the first trimester of pregnancy, during pregnancy, and at child age 0 to 2 years is associated with increased blood pressure at age 5 to 12 years, according to a study published in the March 1 issue of Environmental Research.Yu Ni, Ph.D., from San Diego State University, and colleagues examined the association between exposures to fine particulate matter (PM2.5) and nitrogen dioxide (NO2) and blood pressure measured at ages 5 to 12 years in 4,863 U.S. children. Residential exposures were derived from spatiotemporal models with a biweekly resolution and averaged over each trimester, the whole pregnancy, and child age 0 to 2 years.The researchers found that the mean PM2.5 varied from 7.6 to 7.9 µg/m3, and mean NO2 varied from 8.1 to 8.8 ppb across windows. Positive associations were seen for PM2.5 in the first trimester with systolic blood pressure (SBP) percentile (β, 1.92) and risk for high blood pressure (risk ratio, 1.16). There were also associations seen for higher PM2.5 exposures averaged over pregnancy and age 0 to 2 years with elevated SBP percentiles and a higher risk for high BP, although precision was lower. Inverse associations of pregnancy average NO2 with SBP and diastolic BP percentiles were suggested (β, −2.42 and −1.94, respectively)."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," Ni said in a statement.Abstract/Full Text (subscription or payment may be required).Sign up for our weekly HealthDay newsletter