Laryngomalacia is the most common cause of stridor in neonates and infants. It manifests by the dynamic collapse of the larynx, typically the epiglottis, arytenoids, and aryepiglottic folds. The etiology is incompletely understood. It has been postulated to be caused by underdeveloped cartilage supporting the larynx or immature peripheral and central nervous system integration of laryngeal sensory and function.

Laryngomalacia causes a wet-sounding inspiratory stridor that may be aggravated by upper respiratory tract infection, supine position, and activities such as feeding and sleeping. Signs of severe laryngomalacia include apneic episodes, frequent spitting up, feeding difficulties, and poor weight gain.

Symptoms typically present very early within the first few weeks of life and resolve within a year.

The condition is far more common in the pediatric population and is rarely found in adults.