I was worried about this as we had cole's room painted when he was newborn. Asked my dad (who is a safety officer and knows about these sort of things) and he said that it would only be as bad fume wise as walking lo down a busy road full of traffic.
If you are worried, could you try using eggshell instead of gloss - I've used it on most of my woodwork (for peace and quiet lol..dad thinks its better than gloss) and I don't think it smells as bad - its the undercoat thats really stinky and you shouldn't need to use any if you aer just painting over.
Personally I'd wait till the weather is nicer so you can leave windows open all the time, and not put lo in the room you've just painted but other than that i don't think it'll do any harm. I'm painting cole's room in april when i'm off work and my parents are having him overnight so he doesn't have to sleep in a room thats just been painted, but he'll be in it the next night, Its a great excuse to get a lie in the next day too

All I'll do is keep the windows open all day/night when its been painted and overnight too when he's in there if its warm enough. Can't see there being any problems.