
I guess I would have to ask how severe the depression and how long it has lasted?
If the mother is unable to sleep (when the baby allows her), eat or relate to her baby. If she is unable to do these basic things for more than two or three weeks, then she really must get professional help.
On the other hand, baby blues or feeling a little weepy for a few days or a week after the birth is pretty typical especially for a first time mom.
I'll never forget how scared and overwhelmed I felt bringing home my first born for the first time. But the feelings went away over time and I was still able to eat, sleep and relate to the baby.
Hope that answers your question.