In other words, I think the parents should be arrested, not the daughter. If they loved and supported her they would have loved and supported her whether or not she was pregnant. The daughter was a victim of neglect from her parents, which is a form of abuse, and abused daughter maybe went on to kill a baby because she wasn't ready to navigate life on her own, and she was realizing her parents were cruel not to support her or to encourage her honesty.
But they really shouldn't blame bulimia as of cause behind murdering a baby. I know plenty of bulimics that never killed a baby. And I think whether or not the baby was born stillborn, denying its existence and denying care for it during pregnancy is contributory homicide... although I don't know the strict definition of that charge.