Postpartum psychosis is a severe but uncommon mental illness that can occur days or weeks after childbirth. Unlike postnatal depression, which is very common (up to 15% of new mothers) and has consistent, slow to change symptoms, postpartum psychosis is fairly rare, accounting for only a few thousand cases a year, and the symptoms can change within an hour. They range from severe mania to severe depression and can be accompanied by anxiety, rapid mood swings, confusion, agitation, behavior changes (usually out of character extroversion), insomnia, lack of inhibitions, paranoia, delusions, and hallucinations.
Although it's a common misconception, environmental factors such as stress don't appear to have any relationship to who might develop the condition. However, it does appear to have a genetic component. It's also more common in women who have previously suffered from another mental illness, such as a schizophrenia spectrum disorder or bipolar disorder.
Postpartum psychosis is a medical emergency and immediate medical attention should be sought if someone is suspected to have the condition. If the condition is diagnosed, hospital treatment is usually required. Usually, patients are treated with an antipsychotic or a mood stabilizer.