Dysphoric milk ejection reflex to nipple/areolar stimulation, thoughts of the baby or of breastfeeding, or overfull breasts, travels through both brain and bloodstream, causing emotional changes in the brain and the release of milk in the breast. Prolactin, released in a gradual wave that peaks after the beginning of a feeding, is responsible for continued milk production. Dopamine inhibits the release of prolactin, so dopamine levels must drop in order for prolactin levels to rise. Some speculate that the necessary dopamine drop is similar to (and timed with) the oxytocin spike – a sort of negative image – but that in D-MER mothers it
Human milk microbiome genomes are uniquely equipped to metabolize HMOs, which are otherwise indigestible by enzymes of the infant gut, some have suggested a coevolutionary dynamic between HMOs and certain bacteria common in both the milk and infant gastrointestinal microbiomes. Furthermore, relative to other mammalian milks, primate milk, particularly human milk, appears to be unique with respect to the complexity and diversity of its oligosaccharide repertoire. Human milk is typified by greater overall HMO diversity and predominance of oligosaccharides known to promote growth of "Bifidobacterium" in the infant gut. Milk microbiota are thought to play an essential role in programming the infant immune