Re: Baby taken by social worker
From what I have experienced and learned when I was a beginner in the Sims 3, you cannot get your baby back.
Your baby was most likely taken from you due to letting one of his needs drop down too low.
For example, maybe he was starving, or maybe you weren't letting him go to sleep, etc.
Usually when a baby's needs go down too low, a social worker will be sent to your house to take your baby away from you to prevent further neglect.
When my first household (ever) had a baby, I didn't know how to take care of it, therefore his needs went down low and he was taken away by the social worker. When I looked on the internet to see if there was a way to get my baby back, I found many answers saying that you cannot get it back.
So, to answer your question.
From my knowledge, you cannot get your baby back. Sorry.