Neonatal Jaundice

Neonatal jaundice is a common condition in newborns characterized by yellow discoloration of the skin, sclera, and mucous membranes due to elevated serum bilirubin levels. It can be physiological or pathological, depending on onset, severity, and underlying cause.

Definition

Epidemiology

Occurs in approximately 60% of term and 80% of preterm neonates
Physiological jaundice usually appears after 24 hours of life and resolves within 1–2 weeks
Pathological jaundice can appear within the first 24 hours or persist beyond 2 weeks
More common in preterm infants, those with hemolytic disease, or with breastfeeding difficulties
Boys are slightly more frequently affected than girls

Etiology

Physiological: increased bilirubin production from hemolysis of fetal RBCs, immature hepatic conjugation, enterohepatic circulation
Hemolytic: blood group incompatibility (ABO, Rh), G6PD deficiency, spherocytosis
Hepatic: neonatal hepatitis, biliary atresia, metabolic disorders
Infections: sepsis, TORCH infections
Breastfeeding-related: breast milk jaundice or breastfeeding failure

Pathophysiology

Excess production of unconjugated bilirubin from breakdown of fetal hemoglobin
Immature UDP-glucuronyl transferase enzyme limits conjugation in liver
Increased enterohepatic circulation enhances bilirubin reabsorption
Accumulation of unconjugated bilirubin leads to tissue deposition (skin, sclera, CNS in severe cases)
Pathological jaundice may result from hemolysis, impaired conjugation, or obstruction
High bilirubin can cross the blood-brain barrier causing kernicterus