You need to talk to your doctor right away. Percocet is a powerful opiate and your baby is going to be born addicted and will have to go cold turkey right away. Think of how that is going to be for her. Additionally, you could have your baby taken from you because you are abusing prescription drugs without having a prescription.
PLEASE talk to your doctor immediately. Do not wait. You have to stop now and give your baby a chance to get off this drug before she is born. Let the doctor decide how to do this that won't harm her.