It sounds like she's stressed out and is overgrooming them, hence the bald spots. Sometimes they take out their stress by overgrooming others in the cage or themselves. It's called barbering.

Have you separated the male from her? She's probably already pregnant again if he was in there when she gave birth. That can also stress her out if she thinks that she'll have new babies soon and her current babies are still around. It's just not a healthy thing for her, the current litter, or her developing babies.