Of course the simplest and the safest will be to remove every piercing in the belly area during a pregnancy, because in these time the risk of injury is increased.
You could be catched easier or the piercing can grows out. Certainly in this case the canaliculus would accrues with high probability and the piercing must be stitched again after the pregnancy. Further a lot of women wanna beautifies their pregnant belly also with a piercing.