The reason why they make you take out the jewelry is incase anything goes wrong and they need to bring you back to life. I had a friend that when she gave birth she went into shock and died for 2-3 min and was brought back to life, they make you take out your jewelry but just in case of any problems
For labor I don't think so. They may suggest removing the tongue ring, but I don't really know. I'm sure the nose one is fine though. I watched a childbirth video at the hospital, and the girl in the video had a belly button ring in. No idea how she managed to keep it in the whole pregnancy. I had to take mine out pretty early.