I can't offer a lot of advice, besides to maybe discourage talking to him about the "consequences" or "wrongness" of his actions. Here's the thing - He already knows, and besides the life changes he has to make, I guarantee he feels guilty and ashamed about it.
My cousin got pregnant out of wedlock last year (to the guy she had been dating for a long time and they were going to get married anyway, but...still obviously not the best decision as they weren't planning for it) and my grandma lost it. Shunned my cousin, said nasty things (that were apparently in the "right spirit to try and get her to come back to the Lord" but let me tell you, they were not). Now that the baby is here they are doing better and the relationship has gotten better, but there is residual bitterness I am sure.
In my opinion, what's done is done. You can't undo the fact that they got pregnant out of wedlock, so to me there is no use beating the dead horse of what has already happened. You can only go forward. Hopefully that makes sense, I don't mean it to sound harsh and it doesn't seem like that is what you were going to
Just wanted to share a personal experience of how if the past is focused on, it causes a rift in the present relationship. I mean, address it if you must, but certainly do not dwell on it.