DALLAS — Women with chronic hypertension or diabetes before pregnancy faced significantly higher risks of delivering infants with critical congenital heart disease, according to preliminary research to be presented at the American Heart Association's Scientific Sessions 2026.
The analysis of more than 44 million live births in the United States from 2018 through 2024 found that women with chronic hypertension — defined as high blood pressure present before pregnancy or diagnosed before 20 weeks of gestation — were 30% more likely to deliver an infant with critical congenital heart disease, the most severe form of heart defects, compared to women with normal blood pressure. Women with pre-existing Type 1 or Type 2 diabetes before pregnancy had a 48% increased risk of having babies with severe heart defects.
Gestational hypertension, or high blood pressure diagnosed after 20 weeks of pregnancy, was associated with an 8% increased likelihood of critical congenital heart disease. Eclampsia, severe hypertension involving seizures after 20 weeks, was not significantly associated with the condition.
The study also tracked trends over the study period. The prevalence of chronic hypertension in pregnancies rose nearly 48%, from approximately 9.4% in 2018 to 13.9% in 2024. The prevalence of critical congenital heart disease increased about 10%, from 5.8 cases per 10,000 births in 2018 to 6.4 cases per 10,000 births in 2023-2024, representing nearly 4,000 infants annually in the United States.
“Our findings suggest that maternal heart health before and during pregnancy may have a particularly important relationship with fetal heart development,” said study author Saad Ur Rahman, M.D., chief cardiology fellow in the division of cardiovascular medicine at Lahey Clinic of Beth Israel Lahey Health in Burlington, Massachusetts.
The analysis used the CDC's National Vital Statistics System U.S. Natality Public Use Files. Researchers adjusted for maternal demographics, diabetes status, smoking, pregnancy history and pregnancy length. The observational design limits conclusions to identifying associations rather than direct causation.
The findings, while preliminary, add to a growing body of evidence linking maternal health and the intrauterine environment with fetal cardiovascular development. The American Heart Association and American College of Cardiology note that high blood pressure affects approximately 16% of pregnancies and is a leading cause of serious complications and death for both pregnant individuals and their infants worldwide.
Researchers said future studies should explore the biological mechanisms that may explain the link between maternal high blood pressure and CCHD, as well as examine whether CCHD risk is influenced by the timing, severity and treatment of high blood pressure during pregnancy.
The abstract was presented at the American Heart Association's Scientific Sessions 2026, Nov. 6-9 in Chicago. The findings are considered preliminary until published as a full manuscript in a peer-reviewed scientific journal.
