Without wanting to simplify maternal mental health assessment in ANY way shape or form, I wanted to share one of the key questions I use in differentiating anxiety from psychosis. New parents are already struggling with hormones, sleep deprivation, poor eating and heightened stress. Many are terrified to tell anyone about their distressing thoughts for fear they will be ‘locked up’ or their baby taken away. This simple question could potentially make a difference in someone’s care, their experience of mental health clinicians and their life. 
Remember to slay in your lane! This is not about teaching differential diagnosis, nor should you be attempting to make decisions about the mental health of someone else unless you are suitably trained. However, there are many times where health professionals forget to actually look at the person in front of them instead of responding to familiar symptoms/stories/programming.