In the face of stressful life events, polymorphisms in the HMNC1, COMT, MAOT, PRKCB, ESR1, and SLC6A4 genes, in the brain-derived neurotrophic factor (BDNF) gene when the postpartum phase occurs in the months of fall and winter, and the OXT and OXTR genes when mothers who had experienced difficulties as children reportedly had a significant connection with postpartum depression. Here, BDNF is linked to postpartum depression.