He may just be freaked out about being a dad and needs to do things just for the heck of it because soon he won't be able to stay out all night, or see his friends very often. When we first found out that we were expecting, we were in college, and it was finals week. My guy would be gone until 3am almost every night because it stressed him out so much. We didn't talk about it for a while (I'm the kind of person that lets emotions fester inside me until I break down), and I knew that he had an ex girlfriend that worked at the college, so I was a wreck. But we talked about it, and I found out that he was at the college, but he was working on his finals and was super stressed about everything happening at the same time. And we were okay after that.
So don't worry. And make sure you two talk about it.
Good luck. I'm sure everything will be fine. :)
I think you should communicate with him and let him know your feelings before things get worse and you just become accustom to it. If that doesn't work, take action. Stand for what you want now so in the long run it won't be harder to change things between you guys. Good luck and God Bless.