Postpartum Psychosis May Be Inherited

Postpartum psychosis is a serious mental health condition that can occur in the first few weeks after a baby is born, with symptoms such as confusion, hallucinations and sudden mood swings. A study of more than 1.6 million women found that having a sister who had postpartum psychosis increased the risk of the condition, suggesting a genetic influence. However, even in these cases, the chance of developing the condition remains low. The study highlights the importance of further research to understand the genetic and environmental factors involved.

Postpartum psychosis is a very serious mental health condition that can affect some women shortly after the birth of a baby. It is a medical emergency because, if not treated quickly, it can lead to suicidal thoughts or even the risk of the mother harming her own baby.

This condition usually appears in the first few weeks after giving birth, usually within the first month, and manifests quickly and intensely. Symptoms include extreme mood swings (such as euphoria or deep sadness), confused thoughts, difficulty thinking clearly, hallucinations, intense anxiety and insomnia.

Despite its impact, postpartum psychosis is still not recognized as a separate disorder in medical manuals, which makes it difficult to diagnose and treat appropriately.

Scientists are still trying to better understand what causes postpartum psychosis. Since the 19th century, it has been thought that heredity (i.e. family history) may play a role, and that events such as pregnancy, childbirth and breastfeeding may be triggers.

More recently, researchers have begun to study biological factors, such as changes in the brain, immune system and hormonal functioning in women. However, specific genetic causes have not yet been identified.

Some studies have focused on women with bipolar disorder (a condition involving intense mood swings) who have experienced postpartum psychosis, suggesting that there may be a link between the conditions. But there is still some debate as to whether the risk comes from genes, environmental influences (such as stress or social support) or a combination of the two.

This most recent study looked at a large number of women in Sweden to understand whether postpartum psychosis runs in families. The researchers studied more than 1.6 million women and looked at which of them developed postpartum psychosis after their first child.

They focused on sisters and cousins ​​of these women, to see if relatives also had a higher risk of developing the same problem. The idea was to compare whether having a sister with postpartum psychosis would significantly increase the chances of another sister also developing the condition, and whether this would also apply to cousins, who share fewer genes.

The results showed that it did: women who had a sister who had experienced postpartum psychosis were about 10 times more likely to also develop the condition. In the case of cousins, the risk was higher than that of the general population, but it was not statistically significant, that is, the data were not strong enough to say for sure that there is a relationship.

This suggests that genetic factors may indeed play an important role, especially among close family members. However, the overall risk is still relatively low: even with one affected sister, the chance of developing postpartum psychosis was only 1.6%.

In short, this study reinforces the idea that postpartum psychosis may be linked to heredity, especially among sisters. At the same time, it shows that just because a family member has the condition does not necessarily mean that a woman will develop the same problem.

This points to a complex interaction between genes and the environment, and highlights the importance of continuing to study this subject. Understanding these factors better can help identify women at risk and offer preventive support at the time of birth and in the first months of motherhood.

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Familial Risk of Postpartum Psychosis

Adrianna P. Kępińska, Thalia K. Robakis, Keith Humphreys, Xiaoqin Liu, René S. Kahn, Trine Munk-Olsen, Veerle Bergink, and Behrang Mahjani 

American Journal of Psychiatry. 19 May 2025

https://doi.org/10.1176/appi.ajp.20230576

Abstract:

Postpartum psychosis is one of the most severe psychiatric conditions, with high risks of suicide and infanticide if untreated. Although genetic factors contribute to the risk of postpartum psychosis, the extent of familial risk remains to be determined. The authors compared relative recurrence risk across different family relationship types, hypothesizing that relative recurrence risk for postpartum psychosis varies by degree of genetic relatedness and is higher in female full siblings than in cousins. This cohort study consisted of 1,648,759 women from the Swedish nationwide registers, of whom 2,514 (0.15%) experienced postpartum psychosis within 3 months of their first-ever childbirth. The authors estimated the relative recurrence risk of postpartum psychosis for female full siblings and cousins as a measure of familial risk. The relative recurrence risk of postpartum psychosis in full siblings was 10.69 (95% CI=6.60, 16.26) when adjusted for year of and age at childbirth. Although cousins showed an elevated relative recurrence risk, these results did not reach statistical significance (1.78, 95% CI=0.70, 3.62). Despite the higher familial risk of postpartum psychosis among full siblings, the absolute risk for women with an affected sibling was relatively low, estimated at 1.60% within the entire population. The observed increased risk of postpartum psychosis in full siblings suggests both genetic and shared environmental influences. However, the lack of significant results in cousins hampers a more accurate distinction between these factors. Furthermore, despite increased relative recurrence risk in siblings, their overall likelihood of developing postpartum psychosis remains low. 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.