Something else to consider, a girl I know only got stretch marks around her belly piercing, the scar tissue didn't allow her skin to stretch. Also, it may not heal properly because your belly will be expanding
Getting a belly piercing is a bad idea if you are pregnant or trying to conceive. It could heal perfectly fine and be uneventful, but there is a increased chance it will not fully heal and therefore become infected.
A navel piercing, for example, will continue to stretch for the duration of your pregnancy. The stretching will leave the hole open and susceptible to infection.