Which condition is most associated with primary pulmonary hypoplasia?

• A. Intrauterine growth restriction
• B. Neonatal pneumonia
• C. Congenital diaphragmatic hernia
• D. TTN

Answer: (C)

Pulmonary hypoplasia happens when lung development is restricted, especially during fetal life when the lungs need space to grow. The classic cause linked to this condition is congenital diaphragmatic hernia, because a defect in the diaphragm allows abdominal organs to herniate into the chest. That herniation crowding the developing lungs shortens alveolar growth and lowers the lung’s size and vascular bed, leading to hypoplasia and severe pulmonary hypertension after birth. Other options affect lung function after birth or reflect general growth issues, but they don’t classically cause the intrinsic underdevelopment of lung tissue seen with this condition.