Blood Sample Centrifuge
15 December 2017

Increases In Maternal Blood Sugar Raise Congenital Heart Defect Risk, Stanford Study Says

A new study out of Stanford University says that increases in a mother’s blood sugar can lead to a rise in the risk for congenital heart defects in her developing baby. And that’s true even for women who have no prior history of diabetes, according to James Priest, MD, the project’s senior researcher.

Sugar During Early Pregnancy Could Pose Heart Risks For Baby

While diabetes is already an established risk factor for infant heart defects, “most women who have a child with congenital heart disease are not diabetic,” Dr. Priest told Stanford’s News Service. Several previous studies suggested that, in non-diabetic women, blood sugar may still be playing some role in the development of heart defects. The new study, Stanford writes, “is the first to examine this question in the earliest part of pregnancy, when the fetal heart is forming.”

Researcher Testing Blood Samples

To find more information, a team of researchers at Stanford analyzed the medical records from over 19,000 mother-child pairs from the six years between 2009 and 2015, reviewing the results of maternal blood tests and any cardiac disease diagnoses rendered after the child’s birth. In total, 811 of the children were born with congenital heart defects, excluding infants who had been diagnosed with genetic abnormalities that impair the heart’s development.

Narrowing their search, the group focused only on maternal blood tests performed within the first trimester of pregnancy, beginning four weeks before the estimated date of conception. The fetal heart begins to form around 20 days after conception. At around 22 days, the organ has already started to pump blood.

A Clear Increase In CHD Incidence

After controlling for additional factors, the team’s findings became clear. The risk of a congenital heart defect rose along with a mother’s blood glucose levels. For every rise in blood sugar of 10 milligrams per deciliter, the risk that a child would develop a congenital heart defect jumped by 8%. Around 50% of these defects were ventricular or atrial septal defects.

The paper, titled “First Trimester Plasma Glucose Values in Women Without Diabetes are Associated with Risk for Congenital Heart Disease in Offspring,” was published online by the Journal of Pediatrics on December 15, 2017.

“This is important because it is a modifiable risk factor,” the study’s lead author, Dr. Emmi I.T. Helle, told the New York Times. “A mother should exercise during early pregnancy – an hour of walking every day is enough – because we know that exercise improves insulin sensitivity. Maintaining a healthy diet is also very important,” the physician concluded.

Should Pregnant Women Receive Routine Blood Glucose Tests?

The researchers are now crafting a second study to test the relationship again. If they observe a similar correlation, it could have a major impact on the way doctors screen unborn infants for heart disease and treat their mothers.

Today, most women aren’t given blood glucose tests during pregnancy. That’s a measure normally reserved for women who already have diabetes. And while the vast majority of pregnant women receive a different test to screen for gestational diabetes, a form of the disease sparked by pregnancy, that test is only administered after the fetal heart has developed.

With a new association between blood glucose and congenital heart defects, though, it could be a good idea to perform more stringent testing for all women. “We could use blood glucose information to select women for whom a screening of the fetal heart could be helpful,” study senior author James Priest says. “Knowing about defects prenatally improves outcomes because mothers can receive specialized care that increases their babies’ chances of being healthier after birth.”

Sugar Consumption Linked To Childhood Asthma

The research on heart defects comes less than one month after a report in the Annals of the American Thoracic Society, describing a study of 1,068 pregnant women, found a link between the consumption of sugary foods and drinks to an increased risk of childhood asthma. Women who ate an average of 46 grams of sugar per day were around 60% more likely to deliver children who would be diagnosed with asthma than women who ate 21 grams a day. A 12-ounce can of Coke contains about 39 grams of sugar.