Postpartum psychosis is a rare, severe, and dangerous form of postpartum depression that can suddenly develop within the first 3 weeks following childbirth. A woman with postpartum psychosis may feel detached from her baby and other people; have hallucinations involving smell, touch, sight, or hearing; 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 with postpartum psychosis to hide her symptoms from people close to her, though not indefinitely. Untreated postpartum psychosis can worsen rapidly and lead to dangerous, irrational behavior that a woman cannot control.

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