How to handle this?

My brother is only 16 and his girlfriend is 15, the girlfriend is pregnant for two months now. The girl's mother called and told me to go to their house tomorrow to talk about the situitio. I dont know what should I do or say. What are your thoughts about this?
I've been taking care of my youngest brother since he was a baby when my parebt are separated so he is like a son to me now im really sad.