All of the following statements about laryngomalacia are true, Except

Laryngomalacia (congenital laryngeal stridor) is the most common congenital abnormality of the larynx. It is characterized by excessive flaccidity of supraglottic larynx which is sucked in during inspiration producing stridor and sometimes cyanosis. Stridor is increased on crying but subsides on placing the child in the prone position. The cry is normal. The condition manifests at bih or soon after, and usually disappears by 2 years of age. Direct laryngoscopy shows elongated epiglottis, curled upon itself (omega-shaped O). Treatment is conservative. Tracheostomy may be required for some cases of severe respiratory obstruction Ref: PL Dhingra 7th edition of Ear, Nose and Throat; Pg no 333