Only advice I have, is stick with her. If she wants this baby, she's probably going to need you by her side. I won't be easy raising a child at such a young age, but it will all work out. There a teen pregnancy forum on here too, people there might have advice for you..As well as people here who've already been through it. I haven't been through it, but my two cents is just to be there for eachother.
Good luck
keri