Familial risk of postpartum depression.

OBJECTIVE

Many psychiatric diseases have a strong familial aggregation, but it is unknown whether postpartum depression (PPD) without prior psychiatric history aggregates in families.

METHODS

Based on Danish national registers, we constructed a cohort with information on 848,544 singleton deliveries (1996-2017). Women with an episode of PPD were defined as having used antidepressant medication and/or had a hospital contact for depression within 6 months after delivery. Those with psychiatric history prior to the delivery were excluded. We estimated relative risk (RR) of PPD, comparing women with female relatives with and without PPD history, respectively.

RESULTS

Overall, women with a PPD history in female blood relatives had themselves a higher risk of PPD (RR = 1.64, 95% CI 1.16-2.34). Having the first-degree female relative with PPD history was associated with a more than 2.5 times (RR = 2.65, 95% CI 1.79-3.91) increased risk of PPD. However, having the second/third-degree female relative and/or a female non-blood relative with PPD history did not increase the woman's own risk of PPD (RR = 0.58, 95% CI 0.26-1.28, RR = 1.09, 95% CI 0.83-1.44).

CONCLUSION

Postpartum depression aggregates in families with no other psychiatric history, but the findings do not support a strong genetic trait as a major cause. Other possible mechanisms are shared environment and/or health-seeking behavior in close relationships.