The trial of Lindsay Clancy, the Massachusetts mother accused of killing her three young children in January 2023, has drawn national attention to postpartum psychosis, a rare but serious mental illness that remains poorly understood and is not formally classified in psychiatric diagnostic manuals. Clancy does not dispute carrying out the killings but has pleaded not guilty to murder, with her defence arguing she was suffering from psychosis at the time, while prosecutors contend the act was calculated. The case has prompted experts to call for greater recognition and treatment progress for the condition.

Testimony has described how Clancy, in the weeks before the deaths, told her mother and then-husband she was having "thoughts of harming the children", yet appeared to be having "one of her best days" hours before killing Cora, five, Dawson, three, and Callan, eight months old. Experts told the BBC that postpartum psychosis, considered a medical emergency, can involve mania, depression, hallucinations and delusions, and can wax and waning rapidly, meaning sufferers can seem fine one moment and be acutely unwell shortly after. Other women who have experienced the condition, such as Meghan Cliffel, described similarly abrupt onsets of paranoia and hallucination weeks or months after childbirth, underlining how quickly and unpredictably the illness can escalate.