Most common causes*

Transient tachypnea of the newborn

Respiratory distress syndrome (hyaline membrane disease)

Meconium aspiration syndrome

Less common but significant causes

Delayed transition

Infection (e.g., pneumonia, sepsis)

Nonpulmonary causes (e.g., anemia, congenital heart disease, congenital malformation, medications, neurologic or metabolic abnormalities, polycythemia, upper airway obstruction)

Persistent pulmonary hypertension of the newborn

Pneumothorax