I took mine out sometime during first trimester because I knew it was going to come out sooner or later, and I wanted to get used to the look of now having it in. Now at 26 weeks, it almost looks like I have two alien belly buttons because of where my belly button piercing used to be.
I tried just for fun a few weeks ago to put my piercing back in, and while it did go in, it looked completely awkward and not sexy at all. It kind of makes me wish though that I never got my belly button pierced in the first place, now that I have this extra belly button looking hole going on :(.