Not all mothers with PPD are targeting their children, a lot of them are locked onto their husbands. You don't hear about that because it doesn't result in an arrest, it results in a divorce where the depressed person will make literally any accusation to "win." This is not hard, because as the new mother she will get the house, car, and child support. As soon as the idea arises, it's fait accompli, and no lawyer could resist that sort of slam-dunk. Trust me on this, guys don't go around saying "We're trying to get pregnant....so I may be homeless by this time next year."
This is very very common, and you won't hear about it Oprah.
Mental illness doesn't just have stigma it has profit and power, and psychoanalysts call it "secondary gain."