"The conventional wisdom about laryngomalacia is that the noise is more pronounced when the patient is on his or her back (with gravity making the epiglottis fall backwards)... Laryngomalacia becomes symptomatic after the first few weeks of life, and may get louder over the first year, as the child moves air more vigorously. It generally resolves spontaneously by the second year of life."
Try keeping him on his side when sleeping to avoid apnea (on the chest is still not good, but side may be better for him). It only VERY RARELY causes serious breathing problems. Stay on it, keep up on it with your pediatrician, and his larynx should strengthen as he grows and it will go away.
at 2:03 PM on Nov. 19, 2008