Maternal depressive symptom trajectories in the first 12 postpartum months and the associated risk correlates.

Postpartum depression has been known to emerge during the peripartum period or within the first 4-6 weeks of childbirth. However, its long-term progression and the underlying mechanisms of its different trajectories remain poorly understood. This longitudinal study examined the diagnostic stability and changes in 191 mothers who were non-depressed (ND), depressed, or had an adjustment disorder (AD). Fine-meshed repeated measures of depressive symptoms from childbirth through 12 months, along with assessments of mother-infant attachment and perceived stress, revealed distinct trajectories reflecting recovery, persistence, or new onset of depression. Approximately half of the postpartum depression (PPD) cases were found to recover, showing improvement within six months, with no recovery seen in the rest of the cases. Among the initially healthy participants, 4.7% developed major depressive disorder (MDD) within the first postpartum year, while 25.6% of those with early AD developed depression in the same period. Persistent PPD was found to be characterized by the strongest negative affective burden, low attachment, and an accumulation of characteristics including premenstrual syndrome (PMS), prior depression, childhood maltreatment, and low social support. In contrast, the recovering cases reported frequent baby blues and PMS, which can be understood as proxy indicators of a heightened hormonal sensitivity. These findings reveal that, rather than being a static condition confined to the early postpartum period, PPD is a heterogeneous and dynamic process. Close monitoring of new mothers in the first postpartum year combined with robust social support may help improve maternal and infant mental-health outcomes.