How does maternal diabetes affect fetal CHD risk and prognosis?

• A. It increases risk for several defects, such as transposition and outflow tract anomalies; strict glycemic control improves outcomes and reduces risk
• B. It decreases risk
• C. It has no effect
• D. It only affects maternal glucose levels

Answer: (A)

Maternal diabetes creates a high-risk intrauterine environment during early heart development, so hyperglycemia in the first weeks of pregnancy disrupts cardiac formation and increases the risk of congenital heart defects. The association is strongest with pregestational diabetes and with poor glycemic control, and it includes defects such as transposition of the great arteries and other outflow tract anomalies, as well as other common CHDs. Importantly, maintaining strict glycemic control before conception and in early pregnancy reduces this risk and is linked to better fetal outcomes if a CHD occurs. In terms of prognosis, when maternal glucose is well controlled, the overall outlook for a fetus with CHD tends to be better because there is less metabolic stress and fewer associated complications, though the baseline risk remains higher than in pregnancies without diabetes.