Your wife is an adult. As such, she has a responsibility to be actively engaged in managing her bipolar disorder and her post-partum depression. That means keeping her doctors' appointments. That means having a schedule for the week with goals and being able to say, "Here's what I did this week to make progress toward my goals." She might have a goal of spending one hour per day caring for the new baby.
No one gets to say, "I just don't feel like doing anything, so I won't be doing anything." That's not just being depressed. That's being entitled.