Postpartum depression: relation with plasma vasopressin at 6-8 weeks postpartum: a longitudinal correlational study

Abstract Background Postpartum depression is the most important postpartum mood disorder due to its significant effects on infant and family health. Arginine vasopressin (AVP) has been suggested as a hormonal agent involved in depression. The purpose of this study was to investigate the relationship between plasma concentrations of AVP and Edinburgh Postnatal Depression Scale (EPDS) score. Methods This longitudinal correlational study was conducted in 2016–2017 in Darehshahr Township, Ilam Province, Iran. In the first phase, 303 pregnant women who were at 38 weeks, met the inclusion criteria, and were not depressed (according to their Edinburgh Postnatal Depression Scale scores) were included in the study. In the 6–8 weeks’ postpartum follow-up, using the Edinburgh questionnaire, 31 depressed individuals were diagnosed and referred to a psychiatrist for confirmation. The maternal venous blood samples of 24 depressed individuals who still met the inclusion criteria and 66 randomly selected non-depressed subjects was obtained by the researchers to measure AVP plasma concentrations with ELISA assay. Results The mean plasma concentration of AVP was significantly higher in the depressed group (41.35 ± 13.75 ng/ml) than in the non-depressed group (26.01 ± 7.83 ng/ml) (P < 0.001). In a multiple logistic regression model for various parameters, increased Vassopressin levels were associated with increased odds of postpartum depression (OR = 1.15, 95% CI = 1.07–1.24, P = 0.000). Furthermore, multiparity (OR = 5.45, 95% CI = 1.21–24.43, P = 0.027) and no exclusive breastfeeding (OR = 13.06, 95% CI = 1.36–125, P = 0.026) associated with increased odds of postpartum depression. Gender preference (having a baby non-desired and desired sex) decreased odds of postpartum depression (OR = 0.13, 95% CI = 0.02–0.79, P = 0.027 and OR = 0.08, 95% CI = 0.01–0.5, P = 0.007). Conclusion AVP may be a contributor to clinical postpartum depression by affecting the hypothalamic-pituitary-adrenal (HPA) axis activity. Furthermore, primiparous women had significantly lower EPDS scores.