I've had mine done for 11 years. (yeah, a friend pierced them with a hypodermic needle from Fleet Farm when I was 15.. Then repierced professionally when I was 19.. I'm just cool like that

I took them out as soon as some of the nipple sensitivity went down after the first trimester.
I brought this up with my OB on my second visit. She said it shouldn't be a problem at all since the nipple is more like a sieve than a single tube-the scars shouldn't get in the way. She even suggested I could keep them in if I wanted. I decided the nipple rings were sexual, and that would be totally wierd to have baby trying to latch on around them. She agreed.