As the case of mrsho's friend, I think the Mum of the girls did a great job. As for me, I think I would do the same. Everyone might make some wrong decisions, and as her mother, I thinks I have the right to support her, at least mentally, I will let her know that I am her mother, I love her and I will be always on her side whatever decision she makes, of course I will explain to her very clearly what happens if she keeps the baby etc....
I won't leave her alone or force her to do something she doesn't willing to do.