Postpartum psychosis is a rare, severe, and dangerous form of postpartum depression that can suddenly occur within the first 3 weeks following childbirth. A woman who has postpartum psychosis may feel detached from her baby and other people. Or she may have hallucinations involving smell, touch, sight, or hearing. She may have thoughts not based in reality (delusions), display bizarre behavior, or have urges to kill herself and her child or children.

Postpartum psychosis is most likely to affect women who have bipolar disorder, also known as manic-depression, or who have had postpartum psychosis before. It is possible for a woman who has postpartum psychosis to hide her symptoms from people close to her, though not indefinitely. Untreated postpartum psychosis can get worse rapidly and lead to dangerous, irrational behavior that a woman cannot control.

Postpartum psychosis is considered a psychiatric emergency requiring immediate hospitalization and treatment.