Previous studies on this topic—including research by the authors of this paper—have been mixed, including research demonstrating (1) no association between oxytocin during breastfeeding and PND [23], (2) an inverse association between oxytocin during breastfeeding and maternal symptoms of depression and anxiety at 2 months post partum [12], and (3) that oxytocin levels differentially predicted HPA axis reactivity in women with or without mood symptoms [13]. Here, OXT is linked to major depressive disorder.