Children might wind up with high blood pressure due to air pollution exposure that occurred in the womb or the cradle, a new study says.

Exposure to smog before and after birth increases a child’s odds of having higher blood pressure between ages 5 and 12, researchers report in the March 2026 issue of the journal Environmental Research.

The study specifically linked childhood blood pressure to fine particle pollution.

“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,” lead researcher Yu Ni said in a news release. She’s an assistant professor of epidemiology and biostatistics at San Diego State University.

High blood pressure among children is becoming more common, increasing by nearly 80% over the past two decades, researchers said in background notes. It can lead to long-term health problems like heart disease and impaired kidney function.

For the study, researchers analyzed data from more than 4,800 children participating in a National Institutes of Health-funded study on how environmental influences can affect a child’s health.

The researchers compared the children’s health between ages 5 and 12 with outdoor air pollution levels during each trimester of pregnancy, across the full pregnancy, and during the child’s first two years of life.

Children exposed to higher levels of particle pollution before and after birth had higher blood pressure on average, researchers found.

Exposure during the first trimester appeared to have the biggest impact, results showed. 

It was associated with higher systolic blood pressure — the pressure in your arteries when your heart beats — and a greater likelihood of high blood pressure in childhood.

However, moms’ exposure to another type of air pollutant — nitrogen dioxide — was associated with slightly lower blood pressure among children, researchers found. This effect was strongest during mid-to-late pregnancy.

“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.