A recent research was conducted to study the influences of maternal diabetes on fetal heart development. The findings have been published in the journal Birth Defects Research.

Congenital heart disease (CHD) is the most common birth defect. And even with remarkable advances in care, it remains the leading cause of non-infectious death in infants. "Many epidemiological studies have demonstrated a strong correlation between maternal diabetes and increased risk of CHD in babies born to affected mothers," said Dr. Madhumita Basu. "And many factors, including the type of diabetes, other environmental influences, and potentially certain genetic predispositions can influence which CHD subtypes are likely to develop."

For example, type 1 and type 2 diabetes are linked with specific CHD subtypes. Babies born to mothers with type 1 diabetes had a greater association with conotruncal malformations and atrioventricular septal defects. Those born to mothers with type 2 diabetes had the highest risk of heterotaxy and left ventricular outflow tract obstructive malformations. Both types of maternal diabetes also increased the risk of other types of CHD in the infants, including right ventricular outflow tract obstructive malformations and atrial and ventricular septal defects, albeit to lower levels.

The gestational age at which the fetus is exposed to maternal diabetes is also important. Maternal diabetes before conception and during the first trimester is associated with diabetic embryopathy in the fetus, which affects the heart, great vessels and neural tube. When maternal diabetes develops in the latter half of pregnancy, it is associated with fetal macrosomia, cardiomyopathy, increased incidence of perinatal complications and mortality.

Diabetes is a complex disease, with abnormal homeostasis of multiple components in metabolism that ultimately lead to the overall metabolic syndrome. Despite this complexity, hyperglycemia has been determined to be the primary teratogen in all forms of diabetes. How exactly maternal hyperglycemia causes birth defects in infants is still unknown, however-

"The underlying molecular mechanisms by which alterations in maternal glucose levels act to cause the congenital heart defects are actively under investigation in our lab and others," said Dr. Basu. "We suspect that this gene-environment interaction is related to the dysregulation of specific epigenetic processes in the fetal heart." "We think that maternal diabetes can ultimately affect the levels at which genes are expressed during fetal development," said Dr. Garg.