I want to post a note to let you know that my son was born with a stuffy nose. My husband and I both remember clearly in the delivery room that he was stuffy within a few minutes of being born. I thought it would go away in a few days and it didn't. I have researched for months online trying to find an answer, only to find that "doctors say it is normal and he will grow out of it". Sorry, this answer isn't good enough. There's always a reason when something is out of the ordinary. He is my fourth child and my other three have not had this.
I found a theory that it could perhaps be that he is dairy/lactose intolerant. I tried cutting out all dairy from my diet (he is breastfed) only to see his stuffiness slightly subside but never go away completely, and after a time, flare up again even though I wasn't having any dairy products at all, and nothing with dairy even in it (milk, by the way, is in practically everything!).
He was only stuffy at night, even waking around 4am unable to breathe. I would sit up and hold him while he slept. It was very frustrating because I knew there had to be an answer somewhere. I have looked and looked and looked at what feels like hundreds of posts inquiring of the same thing without any helpful answer.
A friend suggested a theory. So, three weeks ago I began taking a vitamin supplement called "Betain HCL" (I bought it from a local health food store) with every meal. This is to help level out my stomach acids. This therefore means there is nothing wrong with my son, but with me that needed to be fixed. Now that I've found a remedy (very easy remedy mind you) his stuffiness has completely dissipated, which is the first time since being in this world. He is now five months old.
The reason it may seem that a baby may grow out of it, is because when you stop breastfeeding the baby is no longer affected by your own body's digestion.