Is it safe to put a christmas tree in a childs bedroom?

I assume you're referring to a real tree and not a plastic one. I'm not in favor of having a tree in a youngster's bedroom as pine needles are strewn around and mold can grow on the tree triggering symptoms in such an enclosed space.

There is a potential for pine needles, and lights may be a fire hazard. The tree may be located in a common area, and allow your child to consider it their own. Keep the tree well hydrated.