I don't think this is an etiquette issue, it is a friendship issue. You should do whatever you feel is right, balancing your own needs with those of your friends. I personally would clear away most of the baby stuff, and steer conversation away from the baby ("Oh the baby is doing really well, she just *blah blah blah*, but we were definitely ready for an adult night with our friends!"), but you would not be wrong to do otherwise. This is a delicate situation, you can get through it with love and sensitivity.
Don't act like you are ashamed of the baby or anything, just acknowledge and then change the subject. They know you have a child and they are happy for you, they just don't want to think too closely about how you have a baby and they don't.