PPHN is most commonly seen in which group?

• A. Full-term babies
• B. Preterm infants
• C. Small for gestational age infants
• D. Post-term infants

Answer: (A)

Persistent pulmonary hypertension of the newborn happens when the normal drop in pulmonary vascular resistance after birth fails to occur, so blood keeps shunting right-to-left through the PDA and foramen ovale. This pattern is most commonly seen in full-term or near-term infants, where risk factors like meconium aspiration, sepsis, pneumonia, or other hypoxic stresses are more likely to be present. In preterm babies, the dominant problem is immature lungs and surfactant deficiency leading to respiratory distress syndrome, rather than the typical PPHN physiology, so PPHN is less common there. Small-for-gestational-age infants can have many complications, but PPHN is not the classic primary presentation, and post-term status doesn’t by itself drive PPHN as strongly as term-associated risk factors.