I personally didn't have my belly ring when I got pregnant but I have had two friends that have kept theres in through the whole pregnancy they just switched to the plastic rings because they seemed to give and move a little better.
I think you can buy actual pregnancy belly button rings online so you don't have to take it out if you don't want to.
When I still had my belly pierced I had a maternity bar in. They make you remove them for scans but it fit throughout my pregnancy ☺
With my first 2 babies I wore it throughout pregnancy. I bought one online that was plastic, like a flexible piece of tubing with plastic balls. I wore that only for the 3rd tri. It was fine no pain or anything. My mil kept saying my babies would come out with dents in their heads, silly in laws.
I kept mine through my whole pregnancy the hole stretched a little though but nothing major I couldn't fine a plastic one anywhere
I made a huge mistake and kept a regular one in the whole time, my belly button looks super weird now :-(