"This finding may have a profound effect on how pregnant women are screened and treated -- not only for diabetes, but also for elevated blood sugar levels during pregnancy," said Dr. Barry Goldberg, a child heart specialist who reviewed the new study. He's chief of pediatric cardiology at Southside Hospital in Bay Shore, N.Y.
As Goldberg explained, "congenital heart disease occurs when the heart fails to develop normally during fetal life. It is the most common birth defect, affecting approximately eight out of every 1,000 births, or about 1 percent. While many defects are mild, others can be devastating and life-threatening."
It was already known that diabetes increased a pregnant woman's risk of having a baby with a heart defect, but this study is the first to look at how elevated blood sugar levels -- without diabetes -- might affect that risk.
The new research was led by Dr. James Priest, assistant professor of pediatric cardiology at Stanford University. His team tracked the medical records of thousands of mothers and their babies born between 2009 and 2015.
Among women who did not have diabetes before or during pregnancy, the risk of having a child with a congenital heart defect rose 8 percent for every 10 milligrams-per-deciliter increase in blood sugar (glucose) levels in the early stages of pregnancy, the researchers found.
"Most women who have a child with congenital heart disease are not diabetic," Priest noted in a university news release.
"We found that in women who don't already have diabetes or develop diabetes during pregnancy, we can still measure risk for having a child with congenital heart disease by looking at their glucose values during the first trimester of pregnancy," he said.
Another pediatrician agreed the findings are important, but added that they need to be verified.
The study is a retrospective look at medical records -- not the "gold standard" prospective trial that's needed to prove cause-and-effect, said Dr. Michael Grosso, chair of pediatrics at Huntington Hospital in Huntington, N.Y.
"The findings now need to be replicated in a prospective study to be sure that the association is truly causal," Grosso said.
Priest's group plans to do that as their next phase in this research.
If the link between maternal blood sugar levels and heart defects is proven, it could change obstetric care, Goldberg said.
"Earlier and more aggressive management of blood sugar may result in a dramatic decrease in the incidence of congenital heart disease and save the lives of countless newborn babies," he said.
The study appears in the Dec. 15 online edition of The Journal of Pediatrics.More information
The U.S. Centers for Disease Control and Prevention has more on congenital heart defects.
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