I personally don't think there's anything wrong with a parent taking a bath with their child. My mother took baths with me until I was about 3 or so, then she just started supervising until I was old enough to bath myself (She still had to come in to wash my hair for me until I was 8 though, I couldn't do it without using too much shampoo and getting a lot of it in my eyes).

Although, I do think its time that you started supervising with your daughter. She's at the age where she really needs to start learning how to do some little things by herself.

Congrats on the baby by the way.