Diagnosis of early and late PPD
PPD was diagnosed using a semi structured interview (DIGS) (30), according to DSM-5 criteria for a major depressive episode (31). PPD was evaluated at two time points: at 8 weeks postpartum (early PPD), and at one year postpartum (late depression). Early PPD was defined as beginning prior to the 6th week postpartum, and was diagnosed at 8 weeks. Late PPD was defined as beginning between two months and one year postpartum: women were assessed at the one year follow-up for the onset and duration of depressive symptoms over the prior 10 months. Thus, late PPD was assessed retrospectively one year after delivery, and could persist at the time of assessment or not.
For all PPD, the date of onset and the duration of symptoms were collected.