I think there is a lot of jumping to extreme conclusions here about OP's friend and her pregnancy, be it wanted, unwanted or whatever.
The only thing that is obvious from OP's post is that friend has cut ties with her, and most likely with other friends since the pregnancy.
As PPs have said they have also experienced this in a normal, wanted pregnancy, I think it is unfair to assume that the pregnancy was unwanted or was a result of a tragedy.
I agree that the OP does not need to chase this friend anymore. You can't force somebody to be your friend.
I think the ball is in friend's court right now, but that OP should be prepared that she may not hear from her again in a long, long time.
I'm sorry you have to go through this, OP. Ignoring you on the street is harsh.