The Risks to Infants of Diabetic Mothers

Newborns born to diabetic mothers are at an increased risk for a variety of complications. Most of these can be attributed to high maternal blood glucose levels. In the presence of severe maternal ketoacidosis the risk of fetal death increases to 50%. In the acidic environment created by ketoacidosis the enzyme systems of the fetus will cease to function.

The incidence of congenital defects is diabetic pregnancies is 5% to 10%

and is the major cause of death for infants of diabetic mothers. Research suggests that this increased incidence of congenital defects is related to multiple factors including high glucose levels in early pregnancy.

The defects are often found in the heart, central nervous system, and skeletal system. In the heart Septal defects, coarctation of the aorta, and transposition of the great vessels are the most common defects caused by a diabetic pregnancy. Central nervous system defects include hydrochepalus, meningomyelocele, and ancephaly. There is also on defect that is specific to infants born to diabetic mothers. Sacral agenisis is a disorder in which the sacrum and lumbar spine do not develop causing the lower extremities to not develop completely. Preconception counseling and tight blood glucose control before and during the first trimester is the best way to reduce the risk of these types of defects.

Another condition that infants born to diabetic mothers are at risk for is macrosomia, which is excessive growth and storing of fat. These babies are at risk of being large for their gestational age if their mother's blood glucose levels are not kept under control. High maternal blood glucose levels leads to an increase of glucose crossing the placenta to the fetus. The fetus responds by producing large amounts of insulin leading to hyperinsulinism and hyperglycemia which are the primary cause of macrosomic babies. Because these babies are abnormally large they are usually delivered by c-section to reduce the risk of trauma associated with a vaginal delivery.

If the diabetic mother's vascular system is compromised then the infant may suffer from intrauterine growth restriction (IUGR). This leads to small for gestational age babies because the vascular changes in the mother decreases the blood supply to the placenta which in turn restricts the nutrients the fetus need to grow at a normal rate.

Respiratory distress syndrome is another risk brought about by high fetal insulin levels. The overabundance of insulin inhibits some fetal enzymes needed for surfactant production. Surfactant is complex substance that lines the lungs and is necessary for newborns to be able to breathe when born.

Polycythemia, an over production of red blood cells, is also a risk for newborns of mothers with diabetes. This is a result of a diminished ability of glycosylated hemoglobin in the mother's blood to release oxygen. Polcythemia in turn can cause hyperbilirubinemia because immature liver enzymes are unable to metabolize the increased bilirubin created by the excess red blood cells.