Joyous_L - I have really long nails, and have been doing acrylic overlays for about two years as I was tired of breaking one, and then having to cut the other nine down to match and wait for them all to grow.
Now may nails are about 7mm long from the tip of my finger, but they are often in the region of 10 - 13mm which is ridiculously long.
I did the overlays during my last pregnancy and beyond and did not have any problem, and mentioned it to my OBGYN.
I would imagine that sitting in the salon all day with that stuff around you is not great, but exposure for a limited period every 2/3 weeks for an hour is not going to be harmful.
I did however find the smell of the acrylic and the salon very strong while pregnant and I did have to try to stop myself up-chucking, but other wise fine.
People often comment as to how I can handle a baby with long nails, but it is fine.
I must confess though that with a newborn and the cream and wiping bums and the like, it is easier if you cut them right down, as you are always digging kunk out from under your nails - and some days the bum cream and the poop looks deceivingly similiar as it sits under my nail.