Postpartum mood disorders may be related to a decreased insulin level after delivery.

Postpartum mood disorders are very frequent complications of delivery. The prevalence of postpartum blue syndrome is around 25% and that of postpartum depression is around 10%. These disorders greatly affect the well-being of these newly delivering mothers. Currently, the etiology of postpartum mood disorders is still unknown. Although many hormones have been investigated for their possible roles in postpartum mood disorders, the results are still inconclusive. Several studies have shown that insulin increases gradually during pregnancy. The level of insulin secretion may double by the third trimester. Insulin level reaches a maximum before delivery and returns to the level before pregnancy after delivery. The drop in the insulin level during the postpartum period appears to be more sudden and abrupt than the rise of insulin level during pregnancy. Recent studies have showed that insulin affects the secretion of serotonin in the brain. While serotonergic nervous system is well known for its important role in the development of mood disorders, decreased insulin level may induce mood disorders through the mechanism of affecting serotonin secretion in the brain. In the current paper, we propose that the rapid decrease in insulin level during the postpartum period may be one of the causes of postpartum mood disorders. If the hypothesis is valid, clinicians may be able to prevent postpartum mood disorders by carbohydrate-rich food during the postpartum period to stimulate the secretion of insulin. A carbohydrate-rich diet may also become an adjunctive therapy in the treatment of postpartum mood disorders according to the present hypothesis.