The development of an offspring can be significantly affected by maternal mental health.¹ The contradicting evidence on the onset of maternal depressive symptoms convolutes the optimal timing for commencing intervention.² To clarify whether maternal depression symptoms emerge in the prepartum or postpartum period, a prospective longitudinal community-based cohort study based on data from 7 pregnant women cohorts collected during pregnancy and up to 2 years postdelivery was conducted.²

Maternal depression in pregnant women can be detrimental to the development of their offspring, resulting in the occurrence of emotional and functional problems during the prepubescence and adolescence of the child.¹ Thus, it is crucial to offer effective prognoses and intervention whether by medications or psychotherapy, to pregnant women who exhibit depression symptoms as they may have far-reaching benefits for child development.¹

Nevertheless, whether the onset of depressive symptoms occurs during the prepartum or postpartum period in pregnant women remains debatable which complicates the optimal timing for interventions.² Some previous clinical studies have highlighted that pregnant women are at a higher risk of depressive episodes during the postpartum period than any other period, with postpartum depression-related suicides accounting for roughly 20% of all postpartum deaths.³ Contrastingly, another study established that maternal depressive symptoms were already present during pregnancy in most cases of postpartum depression, suggesting that these early prepartum depression symptoms were the predecessor and a reliable predictor of postpartum depression.⁴ Due to the conflicting evidence on the onset of maternal depression symptoms, more longitudinal data are required to identify the emergence of maternal depression symptoms, thus determining the optimal timing for initiating intervention.²

A prospective study of community-based cohorts across 3 continents was conducted to examine the timing of onset and stability of maternal depressive symptoms during the perinatal and postnatal periods.² A total of 11,563 pregnant women were screened from pregnancy up to 2 years postdelivery for their self-reported  maternal depressive symptoms assessed by either the Edinburgh Postnatal Depression Scale (EPDS) 8 or the Center for Epidemiological Studies-Depression (CES-D).² A trajectory analysis of inter-individual differences in depressive symptoms across the perinatal period was conducted, where K-means clustering was utilized to identify groups of participants with comparable trajectories, and item response theory (IRT) analysis was selected to analyze each individual’s responses  at each time point.²

Results from the K-means clustering analysis exhibited consistent trajectory trends of maternal depressive symptoms in low, mild, and high symptom level groups of pregnant women across all  7 cohorts.² The projected trajectories obtained from the IRT analysis suggested that maternal depressive symptoms are more apparent in perinatal settings, and subsequently stabilize during the postnatal period.² Moreover, a subgroup of pregnant women with probable depression (defined by an EPDS score cut-off of ≥15 during pregnancy and/or ≥13 after childbirth) also projected similar trends during the perinatal and postnatal periods.² Thus, these results highlighted the consistently elevated emergence of maternal depression symptoms during pregnancy compared to after childbirth, thereby reinforcing the perinatal period being the ideal period for detecting such symptoms and providing interventions.²

In conclusion, the population data provided by this longitudinal study suggested that maternal depressive symptoms, regardless of their symptom levels, manifest more frequently during pregnancy and are retained throughout the 2 years of the postpartum period, even among pregnant women with probable depression.² Public health policies should be revised to reflect the importance of early antenatal screening for depressive symptoms.²