Apnea Due to Systemic Illness
Apnea is a frequent complication of systemic illness in neonates. Infections, anemia, patent ductus arteriosus, inborn errors of metabolism, hypoglycemia, hypermagnesemia, and many other conditions may present with apnea in the neonatal period. Systemic illnesses usually produce central apnea.

Apnea Due to Pulmonary Disease
Pulmonary disease may produce prolonged expiratory apnea. Prolonged expiratory apnea is characterized by absence of airflow into the lungs in the absence of upper airway obstruction despite effective inspiratory and expiratory chest and abdominal movements judged by esophageal pressure changes. The apnea occurs during wakefulness (crying and feeding) or during sleep. The apnea as it appears on polysomnogram is obstructive. Bilateral pneumothorax and pneumonia may be associated with apnea.