A baby of a diabetic mother develops jaundice on day 3. Which single combination of mechanisms best explains the increased jaundice risk in these babies?

Answer: A. Polycythaemia increasing the bilirubin load plus impaired hepatic conjugation

Jaundice in the infant of a diabetic mother

These babies are more prone to neonatal jaundice through two main mechanisms.

Mechanisms

• Polycythaemia: chronic intrauterine hypoxia stimulates erythropoietin, raising the red cell mass; the increased breakdown of red cells increases the bilirubin load.
• Impaired hepatic conjugation of bilirubin in the immature liver.

Significance

• Polycythaemia (and hyperviscosity) also predisposes to persistent pulmonary hypertension and other complications.
• Jaundice is monitored and treated (for example phototherapy) according to bilirubin thresholds.

So both increased production (polycythaemia) and reduced clearance (immature conjugation) contribute.