Severe asthma and on steroids since i was born- do these steroids stunt growth?

Great questions. There have been many studies that show systemic corticosteroids can cause growth suppression.  There have also been studies that show asthma in itself -- especially if not well controlled -- can cause growth suppression. 

According to Massoud Mahmoudi in Allergy & Asthma:  Practical Diagnosis and Management, "Doses of prednisone as small as 0.1 mg/kg administered daily for as short a period as 3 months have resulted in significant suppression of linear growth."

However, it also should be noted that studies also prove most doses of inhaled corticosteroids (like you receive in meds like Advair) do not cause the same side effects as oral or injected corticosteroids, and therefore should not effect your height.

Honestly, though, when I was 15 back in 1985 I was on oral steroids for over a year and my asthma doctor sent me to a bone specialist who had me undergo a bunch of tests to determine how short I would be when I grew up.  He even wanted to take a bone chip out of my hip. I refused that test.  To be honest, I didn't really care about how tall I was going to be when I grew up, I just wanted to get my asthma under control.  I told my doctors to quit testing my bones, and she duly respected my blunt request.  The subject was never brought up again.

However, my doctor did tell me the bone specialist predicted I would grow to be no more than 5'4" tall.  It wasn't something I spent much time stressing about, and in the end that turned out to a good thing, because once I was done growing I was 5'8" tall, a pretty normal height.  I am the shortest in my family, but that's no big deal.

I think what is important for any asthma doctor and asthmatic combo is to do whatever is necessary to get the asthma under control, because the risk of losing a few inches is a good trade off for being able to live a normal, active life even though you have asthma.

I've worried about this too.  My 12 year old son has been on Advair 500 for over 5 years now.  The doctor told us it would slow his growth.  Now she's worried it seems to have stopped the growing so she is sending us to a specialist this summer.

I have been on some form of steroid, oral or inhaled since I was young, and I'd hate to think of how tall I was supposed to be if it does stunt growth (I'm 6'3" now). My younger brother has been on stronger meds than I have pretty much constantly (he was a preemie and showed asthma symptoms almost right away), and he's 6'8" and plays defensive line for KU. We may be exceptions to the rule, but I would say it had more the opposite effect on us.