High Blood Sugar in Pregnancy Linked to Heart Defects

A new study says elevated blood-sugar levels, even those that don't signal gestational diabetes, may be linked to a baby's risk of having a heart defect.

High Blood Sugar in Pregnancy Linked to Heart Defects antoniodiaz/Shutterstock

A new study, published in JAMA Pediatrics, has found a link between elevated blood-sugar levels in pregnancy and a baby's chance of having a congenital heart defect. Although health risks for babies of women with gestational diabetes have been well studied, this is the first research indicating a connection between elevated blood-sugar levels of pregnant women, below the diabetes cutoff, and infant heart defects.

"Diabetes is the tail end of a spectrum of metabolic abnormalities. We already knew that women with diabetes were at significantly increased risk for having children with congenital heart disease. What we now know, thanks to this new research, is that women who have elevated glucose values during pregnancy that don't meet our diagnostic criteria for diabetes also face an increased risk," said the study's lead author, James Priest, M.D., from the Stanford University School of Medicine and Lucile Packard Children's Hospital in a press release.

Two major defects

To reach their conclusions, researchers looked at blood samples from 277 California women in their second trimester of pregnancy. A control group was made up of 180 women carrying fetuses without congenital heart disease. The remaining women were carrying infants with one of two major heart defects: either tetralogy of Fallot, a structural heart problem that doesn't allow enough oxygen to circulate in baby's body, or dextrotransposition of the great arteries, a condition in which the two main arteries carrying blood away from baby's heart are reversed.

Blood samples collected at different times of day measured both blood-glucose and insulin levels. Researchers found women carrying fetuses with tetralogy of Fallot had higher average blood-glucose levels than the control group. Blood-glucose levels were not elevated in the women with babies who had dextrotransposition of the great arteries. But interestingly, those women had significantly elevated insulin levels.

Preventing the problem

Dr. Priest told Fit Pregnancy that more studies need to be done, but "if the relationship between blood sugar levels and risk of heart malformations are confirmed, early glucose screening may help identify women who are at a higher risk for having a child with congenital heart disease even if the mothers don't have a clear diagnosis of diabetes. This could help obstetricians and pediatric cardiologists identify additional women who may be at increased risk of having a child with congenital heart disease, and perform appropriate fetal echocardiography to make early diagnoses."

"For most women, maintaining a healthy diet with a low glycemic index and an appropriate amount of moderate exercise are widely accepted as safe and effective measures for controlling blood sugar levels before and during pregnancy," Dr. Priest says. "For any woman who is pregnant or considering becoming pregnant, I would advise them to speak with their health care providers about how to plan a healthy diet that ensures appropriate weight gain during pregnancy."

Related: 10 Easy Ways to Upgrade Your Pregnancy Diet