Risk for Postpartum Psychosis Higher When Full Sibling Has Experienced It

Despite increased relative recurrence risk in siblings, overall likelihood of postpartum psychosis remains low

By Lori Solomon HealthDay Reporter

THURSDAY, May 29, 2025 (HealthDay News) — Women with a sister who experienced postpartum psychosis may be 10 times more likely to have it themselves, according to a study published online May 19 in the American Journal of Psychiatry.

Adrianna P. Kępińska, Ph.D., from the Icahn School of Medicine at Mount Sinai in New York City, and colleagues compared the relative recurrence risk for postpartum psychosis across different family relationship types. The analysis included roughly 1.6 million women identified from Swedish nationwide registers, including 0.15 percent who experienced postpartum psychosis within three months of their first-ever childbirth.

The researchers found that the relative recurrence risk for postpartum psychosis in full siblings was 10.69 when adjusting for year of and age at childbirth. There was a trend toward a higher relative recurrence risk among cousins, but these results did not reach statistical significance. The absolute risk for women with an affected sibling was relatively low (1.60 percent within the entire population), despite the higher familial risk.

“The observed increased risk of postpartum psychosis in full siblings suggests both genetic and shared environmental influences,” the authors write. “This study underscores the need for further research to better understand the intricate interplay of genetics and shared environment in the development of postpartum psychosis.”

One author disclosed serving as a speaker for Lundbeck.