Last minute 36 week growth scan because of asthma???

Al

So one of the nurses at the hospital just called and said I need to schedule a 36 week growth scan. I asked if there was any particular reason and she said there isn’t anything written in detail, but it is written under my asthma so that might be why. Is there a reason why my asthma might effect my babies growth? Should I be worried? I’m kinda starting to freak. My doctor has never said anything about my asthma and the baby