Hi L.,
My daughter had laryngomalacia as well, we noticed it as soon as she came home from the hospital. She also had serious reflux which seemed to exacerbate the noisy breathing. It's true that in certain positions it seems to be less noticeable. The noise you are hearing is called a stridor and what was going on in my daughter's case was that she had soft tissue instead of cartilage in her larynx. THough it caused me enormous worry during her first few months, the noise very gradually subsided..it took about 2 1/2 years before I realized that it was almost completely gone. If your son does have laryngomalacia, he will outgrow it. It's hard to not be worried when you hear that noise, but it is not a serious problem..he will be fine. My daughter is now four and there is no sign of it except when she is very excited or has been exercising hard. She was a late talker, but speaks well now, and likes to sing. So it has not permanently affected her breathing or her voice. Occasionally she snores. When she was an infant, she snored so loud at night she would wake herself up sometimes (and me). After a while I got used to it, and I'd wake up if I didn't hear her snoring! I don't know if there is a relationship between reflux and laryngomalacia, but my daughter had to be fed Alimentum too with the cereal mixed in, and we would prop her up in a baby papasan chair or her car seat. She also has scoliosis, which is another problem entirely. I think you might have peace of mind if you saw a specialist, an ENT who can monitor his progress. I was lucky that my pedi was experienced and recognized right away that my daughter had laryngomalacia. He referred me to an ENT who was wonderful. Good luck.