Welcome to BYC!!! How many baby chicks do you have and how old are they? Are they possibly overcrowded? The bald spot will grow back if its given a chance. If the other chickens in the pen are pecking at it, the bald spot will only get worse. We sometime have to separate the babies that are getting picked on for a few days till their feathers grow back. Sometimes we have to separate them for weeks.
Good Luck!!!!