Babies born with heart defects may be at increased risk for cancer within the first 10 years of life, according to new research that suggests mothers may also be at risk, American Heart Association reported.

"Our research highlights the importance of maternal factors and genetic traits and understanding how they may be connected," study author Dr. June Huh said in a news release. Huh is a professor of cardiology in the department of pediatrics at the Heart Vascular Stroke Institute at Sungkyunkwan University School of Medicine in Seoul.

Heart defects are the most common type of birth defect in the U.S. In North America, heart defects affect 12 of every 1,000 live births, according to American Heart Association statistics. These include structural abnormalities, such as openings between the heart's chambers, and severe malformations, such as the absence of heart chambers or valves.

Medical advances have allowed children with heart defects to live longer than they once did, but some research suggests they may be at higher risk for other conditions, such as cancer.

In the study, published Monday in the AHA journal Circulation, researchers analyzed health data for more than 3.5 million live births in the Korean National Health Insurance Service database between 2005 and 2019. The newborns and their mothers were followed for a median period of 10 years.

Overall, children born with a heart abnormality had a 66% higher incidence of cancer in their first decade of life than those without heart defects. Cancer risk was more than double in newborns with heart defects involving blood vessels or heart valves and twice as high among those with complex heart defects compared to newborns without heart defects.

Leukemia and non-Hodgkin lymphoma were the most common types of cancer to be diagnosed among children both with and without heart defects.

Mothers, too, faced a higher cancer risk after giving birth to babies with heart defects. They were 17% more likely to be diagnosed with cancer in the decade that followed than women who gave birth to children with healthy hearts.

Researchers don't yet understand the mechanisms that may be responsible for this link but say it could be due to the mother's genetic predisposition to cancer or a mutation that's contributing to both cancer and congenital heart defect risks in newborns.

"The genetic variants inherited from the mother may provide the necessary environment for cancer to develop in congenital heart defect patients, highlighting a possible shared genetic pathway underlying both conditions," Huh said.

Dr. Keila N. Lopez, a pediatric cardiologist at Texas Children's Hospital in Houston, said in the news release that she was surprised by the study's finding of a cancer association among mothers of infants with heart defects.

"This finding needs to be further explored to understand if there are environmental factors affecting genes (epigenetics) or stress-related changes linking congenital heart defects with maternal cancer risk," said Lopez, who was not involved in the research.

"There is some data that suggests stress is related to cancer risk, and having a child with a congenital heart defect can be very stressful," she said. "So having studies that investigate and demonstrate all the links between cancer and congenital heart defects will help us understand lifelong risks of not only heart defects but also the development of cancer within families."

The study, Lopez said, also emphasizes the importance of seeing a pediatric cardiologist and primary care physician for follow-up care, including lifelong surveillance for children born with heart defects.