Dose–response association between perinatal 25(OH)D status and postpartum depression

BACKGROUND: Postpartum depression (PPD) is a common perinatal disorder that affects maternal and child health. Although vitamin D deficiency has been linked to depressive symptoms, the dose‑response relationship between perinatal serum 25(OH)D and PPD and predictive value remains unclear. OBJECTIVE: To investigate the dose‑response relationship between perinatal 25(OH)D and PPD and evaluate its predictive value. METHODS: A total of 326 perinatal women were enrolled, PPD was assessed within 6 weeks postpartum, and serum 25(OH)D was measured at 24-48 hours after delivery. Analyses included baseline characteristics, EPDS scores, risk factors, dose‑response, predictive performance, and interactions with supplementation. RESULTS: < 0.001). Primiparity and fair spousal relationship were risk factors; planned pregnancy, sunlight, and oral supplementation were protective. Positive interactions with sunlight and supplementation were observed, with linear dose‑response. The AUC was 0.822, with an optimal cutoff of 24.26 ng/mL (sensitivity 67.11%, specificity 85.20%). CONCLUSION: Perinatal 25(OH)D levels are linearly and negatively correlated with PPD risk and show good screening utility; exogenous supplementation appears to modify this protective effect.