(HealthDay News) — Women who have a baby with a congenital heart defect may face a heightened risk of heart disease years later, a large study suggests.

Researchers found that among more than 1 million women, those who’d given birth to a baby with a heart defect were up to 43 percent more likely to be hospitalized for heart problems over the next 25 years.

The study is the first to link newborn heart defects to heart disease in moms. And experts said the reasons for the findings are unclear.

“I think women should be aware of the findings, but not worried by them,” said Dr. Mary Ann Bauman, a spokesperson for the American Heart Association who was not involved in the research.

The study had some limitations, Bauman said. For example, the researchers could not examine whether smoking at least partly explained the connection: The habit can raise the risks of both congenital heart defects and heart disease in adults.

It is plausible, however, that a child’s heart issues contribute to a mother’s risk of heart disease down the road.

“The mother’s whole focus is on her child,” Bauman said. Because of that, she added, their own health concerns could fall by the wayside.

Plus, Bauman noted, there’s a potential role for chronic stress — both emotional and financial — especially if a child has a more-severe heart defect that requires repeat procedures and hospitalizations.

The bottom line, according to Bauman, is that mothers should be reassured that they have “permission” to take care of themselves.

“Takinag care of your own health does not mean you’re neglecting your child,” she said.

Worldwide, congenital heart defects affect nearly eight in every 1,000 newborns. That makes them the most common form of birth defect, according to the researchers on the study — led by Dr. Nathalie Auger, of the University of Montreal.

But until now, it hasn’t been clear whether the mothers of those babies have any particular risk of developing heart disease themselves, the researchers noted.

The study findings are based on medical records for over 1 million women who gave birth in Quebec, Canada, between 1989 and 2013. Of those women, 16,400 had a baby with a heart defect.

In most cases, the defects were relatively mild ones where treatment could be delayed or was not needed at all. But just over 1,500 babies had “critical” defects — such as obstructions between the heart and lungs, and holes between the chambers of the heart — that required immediate treatment.

Over the next 25 years, moms of those babies were more likely to be hospitalized for a heart attack, heart failure or other cardiac problems, the investigators found.

Among women whose babies had critical heart defects, there were about 3.4 hospitalizations for every 1,000 women each year, according to the report. That figure was 3.2 per 1,000 among moms of babies with less-severe defects — and 2.4 per 1,000 among women whose babies were free of heart defects.

The researchers weighed other factors — including the women’s age when they gave birth, and documented health issues such as diabetes, obesity and depression — both during and after pregnancy.

Those factors, it turned out, did not fully explain the link between congenital heart defects and heart disease in mothers. Moms of babies with critical defects were still 43 percent more likely to be hospitalized for heart problems, compared to moms of babies without heart defects.

If their baby had a less-serious heart defect, the risk was 24 percent higher, the findings showed.

Dr. Ali Zaidi directs the adult congenital heart disease program at Montefiore Medical Center in New York City.

Zaidi agreed that women should not be alarmed by the findings. He also said more studies are needed to understand what’s going on — including whether there are roles for genetics, chronic stress or other underlying health issues this study could not address.

Still, Zaidi called the findings “fascinating,” and said they send a message to doctors. “We probably need to put more focus on mothers,” he said. “We should look at their cardiovascular risk and what they can do to mitigate it.”

That, Zaidi noted, includes the steps everyone needs — including healthier eating, regular exercise and better blood pressure control.

The study findings were published online April 2 in the American Heart Association journal Circulation.

More information

The American Heart Association has more on heart disease in women.

SOURCES: Mary Ann Bauman, M.D., spokesperson, American Heart Association, Dallas; Ali Zaidi, M.D., director, adult congenital heart disease program, Montefiore Einstein Center for Heart and Vascular Care, and assistant professor, internal medicine and pediatrics, Albert Einstein College of Medicine, New York City; April 2, 2018, Circulation, online