Summary: A major study of more than 1.6 million women found that a woman is over ten times more likely to develop postpartum psychosis if her sister experienced the condition. Postpartum psychosis is a rare but severe psychiatric disorder that can include hallucinations, paranoia, disorganized thinking, and suicidal or infanticidal thoughts if left untreated. The study highlights a strong familial component—especially when bipolar disorder is present—and emphasizes the importance of screening, awareness, and preventive support during the postpartum period.
Although the relative familial risk is high, the absolute risk remains low: researchers estimated the chance of developing postpartum psychosis for a woman with an affected sister at about 1.6%. Still, understanding family history can guide early intervention and targeted mental health care for women at increased risk.
Key facts
- Substantial familial risk: Having a sister with postpartum psychosis raises the risk more than tenfold.
- Interaction with bipolar disorder: Risk increases further—up to about 14 times higher—if a sister has both bipolar disorder and postpartum psychosis.
- Low absolute risk: Despite elevated relative risk, the estimated absolute risk for women with an affected sister is 1.6%.
- Clinical implication: Better awareness and early screening of women with family histories of postpartum psychosis or bipolar disorder may enable prevention and timely treatment.
Source: Mount Sinai Hospital
Mount Sinai researchers report for the first time a striking increase in familial recurrence of postpartum psychosis among full sisters. The findings, published May 19 in the American Journal of Psychiatry and highlighted at the American Psychiatric Association’s annual meeting, suggest both genetic and shared environmental contributions to the disorder.
Postpartum psychosis typically appears within weeks or months after childbirth and is considered one of the most severe postpartum psychiatric conditions. Symptoms often include dramatic mood swings, severe insomnia, hallucinations, delusions, paranoia, confusion, and thoughts of self-harm or harm to the infant. Because the disorder can develop rapidly and has potentially life-threatening consequences, early recognition and intervention are critical.
“Every woman of childbearing age and their physicians need to know about the existence of, severity, symptoms, and familial risk for postpartum psychosis so it can be promptly diagnosed and, hopefully, prevented,” said Veerle Bergink, MD, PhD, Director of the Women’s Mental Health Center at Mount Sinai and co-senior author of the paper. She noted that many high-risk women are unaware of their risk and may lack adequate support during the postpartum period.
The research team analyzed Swedish nationwide registry data covering 1,648,759 women. Among these, 2,514 women (0.15%) experienced postpartum psychosis within three months of their first childbirth. The study estimated relative recurrence risk across different family relationships to determine how risk varied with genetic relatedness.
When adjusted for year and age at childbirth, the relative recurrence risk for postpartum psychosis among female full siblings was estimated at 10.69 (95% CI = 6.60–16.26). Cousins showed an elevated relative recurrence risk of 1.78, but this did not reach statistical significance, limiting the ability to separate genetic from shared environmental effects more precisely.
The analysis also found that bipolar disorder in a sister increased the woman’s risk of postpartum psychosis, and the highest risk—about 14 times greater—was observed when a sister had both bipolar disorder and postpartum psychosis. Despite these elevated relative risks, the absolute probability that a woman with an affected sister will develop postpartum psychosis remained relatively small at approximately 1.6%.
Dr. Bergink emphasized that these results support the view that postpartum psychosis and bipolar disorder, while overlapping, are distinct conditions with specific familial patterns. She and her colleagues hope the data will prompt improved screening practices and proactive support measures for women identified as at higher risk.
The study also lays the groundwork for genetic research to identify the biological mechanisms behind postpartum psychosis. Behrang Mahjani, PhD, Assistant Professor of Psychiatry at the Icahn School of Medicine at Mount Sinai and co-author, is using molecular data to investigate the genetic architecture of the disorder. Determining which genes and biological pathways are involved could reveal whether hormonal or immune factors play a role and may point toward new preventive or therapeutic strategies.
About this postpartum psychosis and genetics research news
Author: Elizabeth Dowling
Source: Mount Sinai Hospital
Contact: Elizabeth Dowling – Mount Sinai Hospital
Image: The image is credited to Neuroscience News
Original Research: Open access. “Familial Risk of Postpartum Psychosis” by Veerle Bergink. American Journal of Psychiatry. DOI: 10.1176/appi.ajp.20230576
Abstract
Familial Risk of Postpartum Psychosis
Objective:
Postpartum psychosis is one of the most severe psychiatric conditions, with high risks of suicide and infanticide if untreated. While genetic factors are thought to contribute, the magnitude of familial risk had not been clearly established. The authors tested whether relative recurrence risk varies by degree of genetic relatedness and is higher in female full siblings than in cousins.
Methods:
This cohort study included 1,648,759 women from Swedish nationwide registers; 2,514 (0.15%) experienced postpartum psychosis within three months of first childbirth. The authors estimated relative recurrence risk for female full siblings and cousins as a measure of familial risk.
Results:
The relative recurrence risk in full siblings was 10.69 (95% CI = 6.60–16.26) after adjustment for childbirth year and maternal age. Cousins showed an elevated but statistically non-significant relative recurrence risk of 1.78 (95% CI = 0.70–3.62). Despite the increased familial risk in full siblings, the absolute risk for women with an affected sibling was estimated at 1.60% within the studied population.
Conclusions:
The increased risk of postpartum psychosis in full siblings points to both genetic and shared environmental influences, though the lack of significant findings in cousins limits precise separation of these factors. Importantly, even with higher relative recurrence risk, the overall probability that a sibling of an affected woman will develop postpartum psychosis remains low. Further research is needed to clarify genetic mechanisms and to develop effective early recognition and prevention strategies.