OXT and postpartum depression: The Mood, Mother and Child (MMC) study (funded by the National Institutes of Health; grant R01HD093901; grant review provided in Multimedia Appendix 1) addresses specific aims regarding the complex roles oxytocin functioning plays within the mother-child dyad, including the role of maternal oxytocin and HPA axis functioning as predictors of postpartum depression and anxiety symptoms (PDAS) and parenting behaviors and the role of child oxytocin functioning as both an outcome, mediator, and moderator of exposure to maternal depression and maladaptive parenting behaviors.