As long as you keep the room well ventilated and don't stay in there for hours I think you'll be fine. Just take breaks, make sure you're staying hydrated and not over doing it, hard to do when painting, but you know what I mean, lol.
I can't remember which brand I got for the nursery, but the important part is that its zero VOC. It does make it more expensive (the paint I got was about 2x as much as "normal paint), but it meant that I could be involved in painting the room instead of having someone else do it. It was nice too that it had virtually NO smell, which meant I didnt' get nauseaus from it! Just ask at your local Lowes, or paint store for a zero VOC paint, and they'll be able to point you in the right direction.
You can use any paint as long as you work slowly and keep all the windows open. I personally though went with the paint they sell at pottery barn kids since its supposed to be safe during pregnancy.