A large new study suggests that smoking during pregnancy could have lasting effects on a child’s heart health.
Researchers found that children whose mothers smoked while pregnant were more likely to have higher blood pressure and a greater risk of developing hypertension as they grew up.
The study, led by scientists from Oregon Health & Science University and Johns Hopkins University, analyzed data from more than 13,000 children across the United States.
The findings were published in the journal Circulation and come from the Environmental influences on Child Health Outcomes (ECHO) Cohort, a major national research program that tracks how early-life exposures affect long-term health.
High blood pressure in childhood is not just a short-term concern. Children with elevated blood pressure are more likely to develop hypertension as adults, which increases the risk of heart disease and stroke.
Researchers have long suspected that smoking during pregnancy might play a role, but earlier studies produced mixed results because they often relied only on mothers’ self-reports or looked at just one part of blood pressure.
In this new research, scientists examined both systolic blood pressure, which measures pressure when the heart beats, and diastolic blood pressure, which measures pressure when the heart relaxes between beats.
They studied children aged 3 to 18 who were born between 1999 and 2020 at 52 research sites nationwide, including Puerto Rico.
To get a clearer picture of prenatal smoking exposure, the team used several sources of information. They combined mothers’ reports, medical records, and urine tests taken during pregnancy.
The urine tests measured cotinine, a substance produced when the body processes nicotine, allowing researchers to confirm whether a mother had actively smoked.
The results showed a clear pattern. Children whose mothers smoked during pregnancy were more likely to have higher blood pressure than those whose mothers did not smoke.
When smoking was confirmed through urine testing, the association was even stronger, affecting both systolic and diastolic blood pressure. The link was particularly noticeable among girls and tended to become stronger as children grew older.
Interestingly, the study did not find a similar effect from secondhand smoke exposure during pregnancy based on mothers’ reports, suggesting that direct smoking may pose the greatest risk.
Scientists believe that tobacco exposure in the womb may affect how a child’s cardiovascular system develops, possibly leading to long-term changes in blood vessel function and blood pressure regulation.
These early effects could persist into adolescence and adulthood.
Researchers say the findings highlight the importance of reducing smoking during pregnancy, not only for the mother’s health but also for the long-term well-being of the child. Preventing prenatal tobacco exposure could help lower rates of high blood pressure later in life and reduce the risk of heart disease across generations.
The study adds to growing evidence that health during pregnancy can shape a child’s future health in powerful ways. For expectant mothers, avoiding tobacco may be one of the most important steps they can take to protect their child’s heart health for years to come.
