Maternal Diabetes and Fetal Heart Development: What Mothers Need to Know

Even with great advances in care, congenital heart disease (CHD) is the most common birth defect. It remains the leading, non-infectious cause of infant deaths. 

What Causes CHD?

CHD is caused by combinations of genetic and environmental factors. Genetic factors, which are found in the DNA of the fetus and are passed on from parents, are increasingly being identified and defined, but non-genetic environmental factors are not as well-understood by the medical community. One of those factors is maternal diabetes.

What Does Maternal Diabetes Do to a Developing Heart?

Diabetes is a complex disease which has a variety of effects on the metabolism and the body overall. Hyperglycemia, or high blood sugar, is a primary contributor to the changes experienced by the fetus. The exact way that hyperglycemia causes birth defects is unknown.

Many studies have shown a strong correlation between maternal diabetes and increased risk of CHD in babies. Both type 1 and type 2 diabetes are associated with CHD, but one study suggests that maybe not always in the same way.

For example, babies born to mothers with type 2 diabetes had a greater risk of abnormal organ placement and CHD as compared those born to mothers with type 1 diabetes.

Most subtypes of CHD were associated with both type 1 and type 2 diabetes. Babies born to mothers with either type had increased risk of malformations with the outflow tract of the heart and holes between the heart chambers.

Why Is the Timing of Maternal Diabetes Important?

When a mother develops diabetes can also affect the baby’s risk level on the various subtypes of CHD. Maternal diabetes before conception or in the first trimester is associated with malformations of multiple organ systems in the fetus.

If the mother develops diabetes in the second or third trimester of the pregnancy the fetus has an elevated risk of larger-than-average birthweight, disease of the heart muscle affecting how it pumps blood to the rest of the body, increased incidence of perinatal complications, and in rare cases, death.

It is thought that maternal diabetes can have a great effect on genes during fetal development. With new technologies in place it is now possible to make discoveries about cellular and molecular changes to the developing heart due to maternal high blood sugar. Unlocking these cellular secrets provides doctors with opportunities to hopefully reduce the risk of the fetus developing CHD.

Researchers hope to translate these findings by screening mothers with risk factors, and their children.