Association between low levels of anti‐inflammatory cytokines during pregnancy and postpartum depression

Aim Previous studies based on a relatively limited number of subjects have indicated potential associations between plasma cytokine concentrations in perinatal women and postpartum depression (PPD). This report aimed to examine alterations in cytokine levels during pregnancy and after delivery by measuring nine cytokines in prenatal and postnatal plasma samples in a large cohort. Methods A nested, case–control study was conducted using plasma samples from 247 women with PPD (Edinburgh Postnatal Depression Scale: EPDS ≥9) and 243 age‐matched control (EPDS ≤2) women from among perinatal women who participated in the Tohoku Medical Megabank three‐generation cohort. Concentrations of nine plasma cytokines (IFN‐γ, IL‐1β, IL‐4, IL‐6, IL‐10, IL‐12p40, IL‐12p70, IL‐13, and TNF‐α) in plasma collected at the time of enrollment during pregnancy and 1 month after delivery were determined using an immunoassay kit. Results Cross‐sectional comparisons of cytokine levels during pregnancy and after delivery indicated that the PPD group maintained significantly lower plasma IL‐4 levels during pregnancy and after delivery than the control group, and that plasma IL‐4 levels decreased significantly during pregnancy regardless of PPD status. Plasma IL‐10 levels were significantly higher during pregnancy than after delivery only among healthy controls, and plasma IL‐10 levels were significantly higher in the control group than in the PPD group. Moreover, IFN‐γ, IL‐6, IL‐12p40, and TNF‐α levels were significantly lower during pregnancy compared with after delivery regardless of PPD status. Conclusions These results suggest a potential protective effect of the anti‐inflammatory cytokines IL‐4 and IL‐10 during pregnancy against the development of PPD.