Neonatology and Perinatal Medicine
What to master
Know fetal-to-neonatal transition: lung fluid clearance, surfactant function, ductal closure, and the shift from placental to pulmonary gas exchange. Understand gestational age assessment, birth weight categories, and the physiology behind respiratory distress syndrome (surfactant deficiency, ground-glass lungs, reticulogranular pattern) versus transient tachypnea of the newborn (delayed fluid clearance, term infant, resolves quickly). Master neonatal jaundice timing: physiologic jaundice peaks after 48–72 hours; jaundice within 24 hours is always pathologic (hemolysis, sepsis, TORCH).
Concepts that recur
Thermoregulation: newborns lose heat by evaporation, conduction, convection, and radiation; know the neutral thermal environment. Hypoglycemia thresholds and at-risk groups (preterm, small for gestational age, infant of diabetic mother). Sepsis presentation is nonspecific-temperature instability, poor feeding, apnea. Understand persistent pulmonary hypertension and the role of inhaled nitric oxide. Know necrotizing enterocolitis risk factors (prematurity, enteral feeding, ischemia) and classic signs (feeding intolerance, bloody stools, pneumatosis intestinalis).
Traps
Questions confuse physiologic with pathologic jaundice by giving a bilirubin value without the hour of life-always interpret against a nomogram. Another trap is apnea of prematurity versus apnea from sepsis or metabolic cause; new apnea after day 7 warrants investigation. Beware routine vitamin K and eye prophylaxis questions testing timing and rationale.
Rule of thumb
For any sick neonate, remember "sepsis until proven otherwise": obtain cultures and start antibiotics before the picture clarifies. For jaundice, ask "what is the age in hours?" before judging the value.