Usual reasons history or suspicion of one or more of the following:
Alcholism
Drug addiction
Mental illness
Previous severe post natal depression/inability to cope
Suidical tendencies or attempts
Child neglect /violence( own)
Child neglect/violence (by current partner or family member)
Domestic abuse (ie of her by partner/vice versa)
All of which could lead them to feel that eiher for the childs safety, or possibly the health of the mother, it is best to take the baby under care for a time, potentially pending full assessment.