['Our aim was to determine whether there is a relationship between serum brain-derived neurotrophic factor (BDNF) and postpartum depression (PPD) in a cohort Chinese population.', 'From May 1, 2014, to September 30, 2014, all eligible women not on medication for depression giving birth at the Fourth Affiliated Hospital of Harbin Medical University were consecutively recruited and followed up for 3 months. At 3 months postpartum, women were screened for depression using the Edinburgh Postnatal Depression Scale (EPDS). The primary outcome measure was an EPDS score of > or =12. Enzyme-linked immunosorbent assay (ELISA) was used to measure serum levels of BDNF at admission. Multivariate analyses were performed using logistic regression models.', 'During the study period, 340 women were enrolled and completed follow-up. In those women, 37 women (10.9%) were considered as meeting criteria for PPD. Serum BDNF levels in women without PPD were significantly higher than those in women with PPD (P<0.0001). Based on the ROC curve, the optimal cutoff value of serum BDNF levels as an indicator for screening of PPD was estimated to be 12.0ng/ml, which yielded a sensitivity of 82.8% and a specificity of 72.6%, with the area under the curve at 0.809 (95%CI, 0.731-0.887). In multivariate analysis, there was an increased risk of PPD associated with BDNF levels ≤12.0ng/ml (OR 7.243, 95% CI: 3.883-12.746; P<0.0001) after adjusting for possible confounders.'] Is serum BDNF concentration after delivery associated with development of postpartum depression : A 3-month follow up study?