Really sorry to hear that 4get, iI only just read the other post. it is so common though.
My next door neighbours have custody of their grandson (their son is his father). The little boy's mum and dad are both junkies and constantly in and out of prison, he was born at just 2lbs and is now a gorgeous little 4year old boy who is going to pre-school. he is so polite and is a real credit to his nanny and grandad.
Sadly, another junkie girl I know went full term and anlthough the baby would have been a healthy weight (over 5lb) she was still born because she'd used throughout the pregnancy.
Sometimes these things happen for a reason, I hope the girl you know uses this as an excuse to get clean and not to use even more (as has happened in both of the situations I mentioned).