After all, for about nine months the focus has been on mom, now the baby bump isn't cute, it's gone and the cute baby is there instead.
For nine months it has been "how are you doing, mom?" and now it's "how's the baby?" that is a little sad at first , isn't it?, and normal too. Understanding that can go a long way toward turning that sadness into joy. If it doesn't, you should talk to your doctor.