Hiya Stace,
I've already had to take my belly peircing out because my bump seems so big and the bar was catching on everything but you can buy belly bars with a long stem that are made specifically for pregnant women. I'll try and find a link for you.
I think your tattoo will be fine, obviously it'll stretch a bit while you're carrying but when baby's born it'll go back to how it was originally.
Good luck with everything x x