According to Hinde, when a baby suckles at its mother’s breast, a vacuum is created. Within that vacuum, the infant’s saliva is sucked back into the mother’s nipple, where receptors in her mammary gland read its signals. This “baby spit backwash,” as she delightfully describes it, contains information about the baby’s immune status. Everything scientists know about physiology indicates that baby spit backwash is one of the ways that breast milk adjusts its immunological composition. If the mammary gland receptors detect the presence of pathogens, they compel the mother’s body to produce antibodies to fight it, and those antibodies travel through breast milk back into the baby’s body, where they target the infection.

At the same time that it is medicine, breast milk is a private conversation between mother and child. While my daughter lacks words, breast-feeding makes it possible for her to tell me exactly what she needs. The messages we are sending each other are literally made of ourselves, and they tell us about what is going on in our lives at that very moment.

Great article from The Stranger