INTRODUCTION: Postpartum mood disorders are heterogenous disorders and comprise postpartum psychosis and postpartum depression. Evidence is accumulating that systemic monocyte/macrophage activation, low-grade inflammation and (premature senescence related) T cell defects increase the risk for mood disorders outside pregnancy by affecting the function of microglia and T cells in the emotional brain (the cortico-limbic system) leading to inadequate mood regulation upon stress.

AREAS COVERED: The evidence in the literature that similar immune dysregulations are present in postpartum mood disorders.

RESULTS: The physiological postpartum period is characterized by a rapid T cell surge and a mild activation of the monocyte/macrophage system. Postpartum mood disorder patients show a diminished T cell surge (including that of T regulatory cells) and an increase in low grade inflammation, that is, an increased inflammatory state of monocytes/macrophages and higher levels of serum pro-inflammatory cytokines.

EXPERT OPINION: Anti-inflammatory agents (e.g. COX-2 inhibitors) and T cell boosting agents (e.g. low-dose IL-2 therapy) should be further investigated as treatment. The hypothesis should be investigated that postpartum mood disorders are active episodes (triggered by changes in the postpartum immuno-endocrine milieu) in ongoing, dynamically fluctuating aberrant neuro-immune-endocrine trajectories leading to mood disorders in women (inheritably) vulnerable to these disorders.