Postpartum depression

I was having a whole discussion with someone about post partum depression and we got into a conversation discussing our views on whether a women with ppd that had thoughts of harming her child and goes ahead and does it deserves to go to jail or not and if it would be faire for her to plead not guilty by reason of insanity or mentally ill, since ppd is probably classified as a mental illness. But even deeper what are your feelings on a women that would do something like that!! We were discussing someone in particular that we both know that had thoughts of drowning her baby but got help... But what if she hadn't  and she had gone ahead and drowned the baby what would you say should happen to her?