Epidemiology of Neonatal Jaundice
Key Point
Physiological jaundice is the most common cause of neonatal jaundice, occurring in 50–60% of term and 80% of preterm neonates.
Mechanism of Physiological Jaundice
Physiological jaundice results from:
- 1.
Increased bilirubin production (shorter RBC lifespan: 70–90 days vs. 120 days in adults; immature reticuloendothelial system)
- 2.
Decreased hepatic uptake and conjugation of bilirubin (low UGT1A1 enzyme activity at birth)
- 3.
Increased enterohepatic circulation (high intestinal β-glucuronidase activity)
Timing and Clinical Features
| Feature | Physiological Jaundice |
|---|
| Onset | After 24 hours of life |
| Peak | Day 3–5 in term infants |
| Duration | Resolves by 1–2 weeks |
| Bilirubin rise | <0.2 mg/dL/hour |
| Infant appearance | Well, feeding normally |
High-YieldNEET PG
Physiological jaundice is benign and self-limited; it does NOT require treatment unless bilirubin exceeds phototherapy thresholds (which depend on age in hours and risk category).
Comparison with Other Causes
| Cause | Onset | Frequency | Key Feature |
|---|
| Physiological | >24 hrs | 50–60% term | Benign, self-limited |
| Breastfeeding jaundice | 3–5 days | 10–15% | Poor latch, inadequate intake |
| ABO incompatibility | <24 hrs | 0.3–1% | Mother O, infant A/B; mild hemolysis |
| Sepsis | Variable | <1% | Ill-appearing, other signs |
Clinical Pearl
A well-appearing neonate with jaundice after 24 hours and a bilirubin rise of <0.2 mg/dL/hour is almost certainly physiological jaundice.
