It has been proven that diabetes in pregnancy increases the chances of congenital heart defects. Yet, new alarming research from The Journal of Pediatrics has shown a link that women, who do not have diabetes but elevated blood sugar levels can have lasting damage also.
“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, the chief of pediatric cardiology, Southside Hospital in Bay Shore, N.Y. who reviewed the new study.
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.”
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.
“Most women who have a child with congenital heart disease are not diabetic,” Priest noted. “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,”
A RESEARCH CHALLENGE
One challenge associated with conducting the research was the fact that maternal blood glucose is not routinely measured in nondiabetic pregnant women. Instead, women typically receive an oral glucose tolerance test halfway through pregnancy to determine whether they have gestational diabetes, but this test is performed well after the fetal heart has formed.
The research team studied medical records from 19,107 pairs of mothers and their babies born between 2009 and 2015. The records included details of the mothers’ prenatal care, including blood test results and any cardiac diagnoses made for the babies during pregnancy or after birth. Infants with certain genetic diseases, those born from multiple pregnancies and those whose mothers had extremely low or high body-mass-index measures were not included in the study. Of the infants in the study, 811 were diagnosed with congenital heart disease, and the remaining 18,296 were not.
The scientists analyzed blood glucose levels from any blood sample collected from the mothers between four weeks prior to the estimated date of conception and the end of the 14th gestational week, just after the completion of the first trimester of pregnancy. These early blood glucose measurements were available for 2,292, or 13 percent, of women in the study. The researchers also looked at the results of oral glucose tolerance tests performed around 20 weeks of gestation, which were available for 9,511, or just under half, of the women in the study.
WHEN RISK IS ELEVATED
After excluding women who had diabetes before pregnancy or who developed it during pregnancy, the results showed that the risk of giving birth to a child with a congenital heart defect was elevated by 8 percent for every increase of 10 milligrams per deciliter in blood glucose levels in the early stages of pregnancy.
The next step in the research is to conduct a prospective study that follows a large group of women through pregnancy to see if the results are confirmed, Priest said. If researchers see the same relationship, it may be helpful to measure blood glucose early in pregnancy in all pregnant women to help determine which individuals are at greater risk for having a baby with a heart defect, he said.
“We could use blood glucose information to select women for whom a screening of the fetal heart could be helpful,” Priest said, adding that modern prenatal imaging allows for detailed diagnoses of many congenital heart defects before birth. “Knowing about defects prenatally improves outcomes because mothers can receive specialized care that increases their babies’ chances of being healthier after birth.”
The work is an example of Stanford Medicine’s focus on precision health, the goal of which is to anticipate and prevent disease in the healthy and precisely diagnose and treat disease in the ill.
- Emmi I.T. Helle, Preston Biegley, Joshua W. Knowles, Joseph B. Leader, Sarah Pendergrass, Wei Yang, Gerald R. Reaven, Gary M. Shaw, Marylyn Ritchie, James R. Priest. First Trimester Plasma Glucose Values in Women without Diabetes are Associated with Risk for Congenital Heart Disease in Offspring. The Journal of Pediatrics, 2017; DOI: 10.1016/j.jpeds.2017.10.046