This is one area that can be a little less forgiving than the rest of your body. Pregnancy is quick weight gain and a lot of stretching over a short period of time. Your tattoo may not be able to adjust as well to these changes, and there could be some damage. Also, keep in mind that in the event a C-section should become necessary when giving birth, your tattoo could undergo even more abuse.
If you think you may have children in the future, it might be wise to wait on that tummy tattoo. The other thing that can cause problems in this area is stretch marks, which is the next topic.