A key question in a Massachusetts murder trial is whether postpartum psychosis drove a mother to kill her three children. Awareness of postpartum psychosis has grown in recent years, but maternal mental health advocates said it's rarely considered in criminal prosecutions. Illinois is the only state with a law allowing for undiagnosed or untreated postpartum depression or postpartum psychosis to be a mitigating factor in sentencing. Experts say it’s important to seek immediate help if you or your partner or family member show signs of postpartum psychosis. Postpartum psychosis is the most severe postpartum psychiatric illness.