When Are 'Horrible Thoughts' a Danger Sign? Experts say that after childbirth, intrusive thoughts are common and mostly benign. Lindsay Clancy’s story provides a disturbing exception. Credit...

Pool photo by Greg Derr When Are 'Horrible Thoughts' a Danger Sign? Experts say that after childbirth, intrusive thoughts are common and mostly benign. Lindsay Clancy’s story provides a disturbing exception. Credit...

Pool photo by Greg Derr Ellen Barry Ellen Barry, who reports on psychiatry, attended the Lindsay Clancy trial for a book about postpartum mental health and the case. During the weeks before she killed her children, as she tried one psychiatric drug regimen after another, Lindsay Clancy kept a careful record of the symptoms that troubled her."Intrusive thoughts," she wrote in her diary on Dec. 8, 2022. The next day, "horrible intrusive thoughts." On the 11th, 12th and 13th, she recorded more "horrible thoughts." By the 14th something had changed; the intensity. "HORRIBLE thoughts," she wrote, underlining both words.

Three and a half years later, Ms. Clancy’s case has put the psychiatric changes women experience in the aftermath of childbirth at the center of a national debate. At her murder trial, which ended in a hung jury, her defense argued that she was psychotic, and could not be held legally responsible for killing her three children; prosecutors argued that she was depressed, but rational. That she was tormented by intrusive thoughts — distressing ideas or images that pop unbidden into a person’s mind — is clear to both sides.

Even the state police seemed to understand their importance; one piece of evidence they collected was a book Ms. Clancy had in her kitchen, called "Good Moms Have Scary Thoughts: A Healing Guide to the Secret Fears of New Mothers." The trial’s focus on intrusive thoughts, a classic symptom of anxiety disorders, has unsettled a consensus in psychiatry and underlined how little is understood about the postpartum brain. Research has emerged in recent years showing that, as the brain prepares for the marathon task of protecting a newborn, nearly every new parent experiences unwanted thoughts of harm to their baby. Experts reassure postpartum women that this does not indicate a risk of violence; indeed, frightening thoughts may produce a protective response, much as a fear of heights may cause someone to reflexively edge back from a cliff.

But Ms. Clancy’s defense has argued that her "horrible thoughts" were something rarer and more alarming: delusions or hallucinations that signaled a spiral into postpartum psychosis. This unusual case, with its tragic outcome, has sent ripples through networks of perinatal specialists, leading some to revisit how to distinguish harmless intrusive thoughts from dangerous ones."I had a lot of certainty before this case," said Karen Kleiman, the author of "Good Moms Have Scary Thoughts." Ms. Kleiman has made it a mission to reassure new parents that intrusive thoughts are normal. She has long recommended a simple test to determine whether such thoughts might signal psychosis: If the patient found the thoughts repellent or horrifying, "we say, 'OK, good, you’re not psychotic.' " "Well, we can’t do that anymore, from this day forward," she said.

Now, she says, she would recommend that clinicians dive deeper, checking for other symptoms like mania, confusion or paranoia. She hasreached out to her publishers to consider making changes to some of the book’s illustrations and text."What we’re really learning is how much we don’t know," she said. "How much the experts don’t know." Image Karen Kleiman, author of "Good Moms Have Scary Thoughts." Lindsay Clancy turned to the book for advice around two months before she killed her children. Scary visions In 2017, when Ms. Kleiman began soliciting women’s accounts of intrusive thoughts on the website for the Postpartum Stress Center, the treatment center she heads outside Philadelphia, the stories flooded in."I’m scared I’ll trip and ...