Getting a tattoo or body piercing of any kind when you are pregnant is a very bad idea. Even though your piercer is using sterile piercing needles, sterile tools and sterile body jewelry (or tattoo needles), you can still develop an infection or complication during healing. The reason why this is not an acceptable risk when pregnant is that any infection you develop can be passed directly onto the unborn child. Most body artists will not work on you if they know you are pregnant.
Any body piercer or tattoo artist that knowingly performs a procedure on a pregnant woman is going against health department protocol and is endangering both you and your unborn child. When you are ready to have the work done (after the baby has been delivered) do yourself a favor and go find another piercer or tattoo artist that cares more about your well-being than your money.