Really interesting points about expectations. Where can society find the balance? I agree that it is not healthy to expect lots of teens to wind up pregnant through carelessness etc, as in the OP. We need to expect people to do whatever is best for them and any children they may have - waiting for the right time FOR THEM (the point being that this differs for everyone) and with the right father of course.
But when teens do become pregnant for the wrong reasons, we cannot just write them off. They need to believe they can go on to great careers etc if they desire it and work hard. Problem is that by then saying this, are we then actually just giving girls the green light to have a baby and say "oh, it'll be fine" without thinking it through?
It's a real headscratcher. 
I agree, obviously, about the feckless fathers... Again, expectations aren't good enough. Society assumes they will run off and not pay support or be involved, and when they do, it's seen as a miracle! I admit I'm guilty of this assumption too - my DSDs' friend has just had a baby at 16 and I was astounded to learn that the father is incredibly involved and is working hard to earn for their son. Mum and baby stay there for part of the week, and they do all the baby care themselves. I was also amazed (and very pleased) to hear she is BFing - despite the overbearing MIL trying to shove a bottle in at every opportunity (
)
It's really brought home to me that I was going by stereotypes... And actually, this situation shouldn't be some miracle, surely it should be standard, for teen parents to do a damn good job 'despite' an accidental pregnancy. It can't do much good to expect them to be lazy, scrounging, abandoning the baby with grandparents etc...
Argh, I don't know, I'm going round in circles. I don't envy policy makers on this one.