Women with PPD were found to have greater ACTH stress reactivity to cold pressor test (CPT), and a significantly elevated ACTH concentration level at 8 weeks postpartum in response to CPT (160), as well as a markedly blunted plasma ACTH response to serial ovine CRH tests at 3, 6, and 12 weeks postpartum (161), and it was suggested that the suppressed ACTH response to ovine CRH might serve as a biochemical marker of the postpartum “blues” or depression (161). This evidence concerns the gene POMC and major depressive disorder.