The biological underpinnings of perinatal depressive symptoms: A multi-systems approach

•Antenatal depressive symptoms were associated with diurnal cortisol variations.•Antenatal depressive symptoms were associated with heightened IL-6 levels.•A disruption of stress-immune circuits might be involved in perinatal depression. Well-established evidence exists of an association between depressive symptoms and alterations in the stress and inflammatory response systems; however, the picture is far less coherent during the perinatal period. This study combines the assessment of multiple stress and inflammatory biomarkers in late pregnancy and after delivery in order to investigate cross-sectional and prospective associations with perinatal depressive symptoms. One-hundred-ten healthy women were assessed in late pregnancy (mean gestational age=34.76; SD=1.12) and 89 were re-evaluated after delivery (mean hours after delivery=52.36; SD=19.70) for depressive and anxiety symptoms through the Edinburgh Postnatal Depression Scale and the State-Trait Anxiety Inventory. Serum Interleukin-6 (IL-6), C-Reactive Protein (CRP) and diurnal salivary cortisol levels were measured on both occasions, while diurnal salivary alpha amylase (sAA) levels were assessed in late pregnancy. Using Hierarchical Linear Models, higher depressive symptoms were found to be associated with higher IL-6 levels, lower morning cortisol levels and a flatter cortisol diurnal slope during pregnancy, while adjusting for potential confounders. No significant associations were found after delivery or with change in biomarker levels from pre- to post-partum. Furthermore, preliminary evidence of a positive association between inflammation and stress markers in women with higher antenatal depressive symptoms was found. The sample was relatively small and highly selected, thus limiting generalizability of the findings. Results emphasize the need for an integrated multi-systems approach to the understanding of the biological underpinnings of perinatal depression and suggest that the stress-immune interactions represent a promising avenue for future endeavor.