If you play really loud music while your pregnant can it cause your baby to go deaf before its born?

No: No. You're asking questions about pregnancy, which is good. I encourage you to learn a lot more about pregnancy, family planning, contraception, and baby and child care from REPUTABLE sources before you become pregnant, because I get the impression from your question that you have a lot to learn.

What did you say?: No, there is no evidence that environmental noises during pregnancy have an effect on neonatal hearing defects. There are other known factors, including certain viral infections (CMV), very high levels of bilirubin and exposure to certain antibiotics. However, hearing loss from loud noises in the mother is a different story - protect your ears with earplugs if you expect to be exposed.