A major new analysis of U.S. birth data has linked chronic hypertension and diabetes present before pregnancy to significantly higher risks of critical congenital heart disease in newborns. The preliminary findings, presented November 2 at the American Heart Association Scientific Sessions 2026, examined more than 44 million live births from 2018 through 2024 and represent one of the largest studies of its kind on maternal cardiometabolic health and fetal heart development.
Key Findings from the Nationwide Dataset
Women with chronic hypertension, defined as high blood pressure before pregnancy or diagnosed before 20 weeks of gestation, faced a 30 percent higher likelihood of delivering an infant with critical congenital heart disease compared with women who had normal blood pressure throughout. Pre-pregnancy Type 1 or Type 2 diabetes was associated with a 48 percent increased risk of severe heart defects. Gestational hypertension, which develops after 20 weeks, carried an 8 percent higher risk, while eclampsia showed no statistically significant association.
Out of the more than 44 million births reviewed, nearly 28,000 infants, or 0.06 percent, received a diagnosis of critical congenital heart disease. These cases require surgical or catheter-based intervention within the first year of life and ongoing specialized cardiac care. Approximately 1.5 percent of the identified cases were statistically linked to chronic or gestational hypertension in the mother.
The study also documented rising trends in maternal hypertension. Its prevalence increased nearly 48 percent during the period, climbing from about 9.4 percent of pregnancies in 2018 to 13.9 percent in 2024. Critical congenital heart disease prevalence rose roughly 10 percent, from 5.8 cases per 10,000 births in 2018 to 6.4 per 10,000 in 2023-2024, equating to nearly 4,000 affected infants annually in the United States.
Context from Earlier Research
These results build on a body of prior evidence connecting maternal chronic conditions to congenital heart defects. A 2013 Canadian population-based study of more than 2.2 million mother-infant pairs found that maternal diabetes mellitus and hypertension were both associated with elevated odds of congenital heart defects, with adjusted odds ratios of 4.65 for Type 1 diabetes and 1.81 for hypertension after controlling for age, parity, and residence. Similar patterns have appeared in Finnish registry data and other large cohorts, where pregestational diabetes showed particularly strong links to specific defect subtypes such as transposition of the great arteries and left ventricular outflow tract obstructions.
The new U.S. analysis distinguishes between hypertension subtypes and focuses specifically on critical congenital heart disease, the most severe category. It also highlights the growing burden of chronic hypertension among pregnant women, a trend that aligns with broader increases in cardiometabolic conditions observed in reproductive-age populations.
Implications for Preconception Care and Public Health
Study author Saad Ur Rahman, M.D., chief cardiology fellow at Lahey Clinic of Beth Israel Lahey Health, noted that the findings point to a meaningful relationship between maternal heart health before and during pregnancy and fetal heart development. He emphasized the value of monitoring blood pressure, discussing heart health with clinicians, and obtaining appropriate care before and during pregnancy to help reduce risks.
Experts have long recommended preconception counseling for women with hypertension or diabetes. Optimizing blood pressure control and glycemic management prior to conception can improve pregnancy outcomes across multiple domains, including reduced rates of preeclampsia, preterm birth, and certain birth defects. The current data reinforce that message by quantifying risks for one of the most serious categories of congenital anomalies.
Public health implications extend beyond individual pregnancies. With hypertension prevalence climbing and critical heart defects affecting thousands of infants each year, health systems may need to expand access to preconception services, particularly in populations with rising rates of obesity, diabetes, and hypertension. Early fetal echocardiography for high-risk pregnancies remains an important tool for prenatal detection and planning.
Broader Maternal Health Trends
The study period overlaps with documented increases in chronic disease among women of childbearing age in many countries. Similar patterns appear in reports on other 2026 health challenges, such as the ongoing dengue outbreak in Bangladesh where deaths have surpassed 233 amid a deadly surge. Like congenital heart defects linked to maternal conditions, dengue complications highlight how underlying health status influences outcomes in vulnerable groups.
Older studies, including a 2020 U.S. cohort analysis of more than 24 million records, found that any maternal hypertensive disorder of pregnancy was associated with roughly 2.5 times higher prevalence of congenital heart disease overall, with diabetes acting as an independent contributor. The consistency across datasets strengthens the case for targeted interventions.
What Happens Next
Because the findings come from an abstract presented at a scientific meeting, they remain preliminary until published in a peer-reviewed journal. Future research is expected to explore biological mechanisms, the roles of blood pressure severity and treatment timing, and whether tighter control of hypertension or diabetes before conception measurably lowers defect rates. Rahman and colleagues also called for studies examining whether the observed associations differ by race, ethnicity, or socioeconomic factors.
For clinicians, the message is straightforward: maternal cardiometabolic health matters for fetal cardiac development. For women planning pregnancy, the data add urgency to managing chronic conditions well in advance of conception. For health policymakers, the rising prevalence of hypertension among pregnant women signals a need for sustained investment in preventive services that reach reproductive-age populations.
Additional context comes from systematic reviews published in 2025 that examined maternal diabetes and congenital heart disease, confirming elevated risks particularly with pre-existing diabetes and underscoring the value of fetal echocardiography in affected pregnancies. These threads together illustrate how chronic conditions established long before pregnancy can shape outcomes for the next generation.
