There are four main protective systems which interact in the skin of the nipple-areolar complex during lactation to maintain skin health and homeostasis.

These are

1. The mammary immune system

2. The microbiomes of the nipple-areolar complex skin, breast milk, and breast stroma (which comprise one system nested within the mammary immune system).

3. Mechanical adaptation of the epidermis to the infant's sucking

4. The protective and wound-healing properties of epidermal and stromal inflammation of the nipple.

From an evolutionary perspective, the nipple and areola have evolved for safe and effective breastfeeding. Our role as clinicians is to understand how to best support the elegant protective functions innate to these four systems, and to protect these four systems from disruptors.

In the photo above, we see the marks on the woman's breast from the pad inside her bra. Her nipple shows subtle signs of inflammation, and (more importantly) she was experiencing pain. This highlights the unique challenges posed by the bra to the breastfeeding woman and her baby.