Chronic Hypertension in Pregnancy Increases Likelihood of Heart Defects

Chronic hypertension during pregnancy was independently associated with higher odds of critical congenital heart disease (CCHD) in infants, while gestational hypertension showed a weaker, borderline association, according to a national cohort study of US live births presented at the American Heart Association (AHA) Scientific Sessions 2026.¹

In fully adjusted models, chronic hypertension was associated with 30% higher odds of CCHD (odds ratio [OR], 1.30; 95% CI, 1.14–1.48), and gestational hypertension with 8% higher odds (OR, 1.08; 95% CI, 0.99–1.18).¹ Predicted absolute CCHD risk was 8.2 per 10,000 births with chronic hypertension vs 6.3 per 10,000 births without hypertension.¹ Prepregnancy diabetes was also associated with CCHD (OR, 1.48; 95% CI, 1.33–1.64).¹

“Our findings suggest that maternal heart health before and during pregnancy may have a particularly important relationship with fetal heart development,” said Saad Ur Rahman, MD, study author and chief cardiology fellow in the division of cardiovascular medicine at Lahey Clinic of Beth Israel Lahey Health in Burlington, Massachusetts. “These results emphasize the importance of monitoring blood pressure, discussing heart health with clinicians and receiving appropriate care before and during pregnancy to reduce the risk of fetal heart defects.”²

Study design and trends in maternal hypertension and CCHD

The investigators used CDC National Vital Statistics System US natality files from 2018 through 2024, comprising approximately 44 million live births classified by the presence or absence of CCHD.^1,2 Maternal hypertensive disorders were categorized as none, gestational, chronic, chronic plus gestational, and eclampsia.¹ Multivariable logistic regression adjusted for maternal demographics, diabetes, smoking, obstetric history, and gestational age.¹

Overall, 27,764 infants were diagnosed with CCHD, a prevalence of 6.3 per 10,000 births.¹ CCHD prevalence rose from 5.8 per 10,000 births in 2018 to 6.4 per 10,000 births in 2023 to 2024.¹ The prevalence of hypertensive disorders of pregnancy increased from 9.4% in 2018 to 13.9% in 2024, driven primarily by chronic hypertension.¹

Sensitivity analyses excluded pregnancies with diabetes and separately restricted the cohort to term births, and both yielded results directionally consistent with the primary analysis.¹

Eclampsia, attributable risk, and limitations of the CCHD analysis

Eclampsia was rare and not significantly associated with CCHD. Approximately 1.5% of CCHD cases were attributable to maternal chronic or gestational hypertension.¹

According to the AHA, the observational design limits conclusions to associations, and birth certificate data do not capture genetic factors, maternal health history, or prenatal imaging. The data also lack information on the timing of hypertension, antihypertensive treatment, blood pressure control, and treatment adherence. The release pointed out the abstract has not been peer-reviewed, and the findings are considered preliminary.²

“This study adds to a growing body of evidence linking maternal health and the intrauterine environment with fetal cardiovascular development,” said Flora Nuñez Gallegos, MD, MPH, a pediatric cardiologist at University of California San Francisco and a member of the AHA’s Council on Lifelong Congenital Heart Disease and Heart Health in the Young, who was not involved in the study. “Although the absolute risk of critical congenital heart disease remains low, these findings highlight the importance of identifying and managing chronic hypertension before and during pregnancy. The association with an infant’s risk of critical congenital heart disease was stronger for chronic hypertension than for gestational hypertension, emphasizing the importance of maternal health even before pregnancy begins.”²

Rahman said future studies should explore biological mechanisms linking maternal hypertension and CCHD and examine whether risk is influenced by the timing, severity, and treatment of hypertension during pregnancy. Hypertension affects approximately 16% of pregnancies, according to the 2025 AHA/American College of Cardiology high blood pressure guideline.²

References

1. Rahman SU, Shaukat MT, Rahman WU, et al. Maternal hypertensive disorders and critical congenital heart disease: a national cohort study of 44 million U.S. live births. Presented at: American Heart Association Scientific Sessions 2026; November 6-9, 2026; Chicago, IL. Abstract MDP1783.

2. American Heart Association. Hypertension or diabetes before pregnancy linked to higher risk of fetal heart defects. Published November 2, 2026. Accessed November 7, 2026. https://newsroom.heart.org/news/hypertension-or-diabetes-before-pregnancy-linked-to-higher-risk-of-fetal-heart-defects