Laryngomalacia, or a soft, floppy upper airway, is the most common cause of noisy breathing in neonates. It is caused by a combination of factors including neuromuscular weakness, cartilaginous inadequacy, and anatomic abnormalities in the voice box. The majority of affected babies' symptoms resolve by one year without intervention, but around 5% of cases require surgical intervention to treat failure to thrive or obstructive sleep apnea.