Diabetes (high blood sugar) raises the risk of fetal congenital heart disease. The higher the mother's blood sugar, the greater the risk.

  • 6-10% of babies born from a diabetic mother have a birth defect. Half of these birth defects are of the heart.
  • A baby may get a thick heart muscle if the mother’s blood sugars are high (late 2nd or 3rd trimester), even if the earlier ultrasound was normal.
  • If hemoglobin A1C is less than 6, the risk of having a child with a birth defect is the same as a non-diabetic mother’s.