Which of the following factors is most strongly associated with an increased risk of neonatal jaundice?

• A. Term birth
• B. Exclusive breastfeeding
• C. Premature birth
• D. Macrosomia (large for gestational age)

Answer: (C)

Immaturity of bilirubin metabolism in preterm infants drives the strongest risk for neonatal jaundice. Bilirubin produced from red blood cell turnover must be conjugated in the liver by the enzyme UDP-glucuronosyltransferase to become water-soluble for excretion. In preterm babies, this hepatic conjugation system is underdeveloped, so unconjugated bilirubin accumulates more easily. Additionally, enterohepatic circulation can be more pronounced and bilirubin production per kilogram is relatively higher in newborns, all pushing bilirubin levels upward. Term infants have more mature liver function, making jaundice less likely, and while exclusive breastfeeding or macrosomia can contribute in some contexts, they do not rise as consistently or as strongly as prematurity.