V1 What causes nipple pain when you're breastfeeding or lactating and there's no visible break in the skin (though there may be pinkness or redness and swelling)
Stretching pressures from poorly distributed vacuum forces in baby's mouth cause nipple pain and damage
The damage women experience is less due to 'tongue pinching and rubbing' – since the tongue is moist, well lubricated by saliva and milk, and applied over the whole undersurface of the NAC and breast – and due to stretching forces being applied to specific areas instead of evenly distributed over the whole of a large mouthful of breast tissue and nipple. When women hear this, many say to me: 'That makes sense. Now I get it. Yes, I can see, there has been a lot of breast tissue drag. That is what's happened to me and my baby.'
Breast tissue drag means that the vacuum forces are reflexly increasing, as the baby's hardwired drive aims to draw up more breast tissue. High tensile forces can be applied to small parts of the surface of the breast and nipple inside the mouth when this happens, instead of being diffused over a large surface area of the nipple and breast tissue, protecting the vulnerable junction at the base of the nipple and areaola, or the face of the nipple where high tensile load may be applied if there is not enough breast tissue drawn up.
At the front of the oral cavity, we want the breast tissue being drawn in to be of such a big volume that the jaw is reasonably open even when the jaw is up: in response to breast tissue volume. But if the baby is dragging on the mother's breast tissue, relative to her normal breastfall, then there is a force pulling back out of the baby's mouth at the front, the vacuum being generated by the jaw drop in the context of the front and back seal can't draw up all the breast tissue that is needed. The jaw will close up higher, because there is less breast tissue at the entrance. The tongue shape on its surface will alter, to conform with the lesser amount of breast tissue drawn in (the mid-tongue shape will look more humped).
This is when we need to get rid of this breast tissue drag, instead of blaming the baby or the woman or a medical condition that one can only control by cutting or burning and hurting. Or by making a woman do exercises on her baby many times a day, instead of just getting on with enjoying him and getting out to have a good day with her friends. Breast tissue drag depends on multiple complex factors, which can be addressed by strategies for fitting a baby into her mother's body.
Babies of women experiencing nipple pain have higher peak intra-oral vacuum pressures. This places the nipple and surrounding breast tissue under substantial tension and elastic strain. The Human Lactation Research Group that that two thirds of women with persistent nipple pain despite fit and hold interventions by IBCLCs were shown to have strong vacuums while breastfeeding. This has been interpreted as cause-and-effect, but I propose that these are the babies who are experiencing breast tissue drag, which also causes the pain, and also which also causes a reflex increased compensatory vacuums acting upon the reduced amounts of breast tissue in the mouth in an attempt to draw up more, but coming up against the counter-force of the breast tissue drag.
Pain is a sign of tissue injury, of stretching and shearing forces between the nipple skin (epidermis and dermis) and underlying collagen, which put the skin at risk of breaking. The shearing may cause bruising (leakage of blood into deeper tissues). The more persistent the pain is, the more significant the microscopic damage from repetitive micro-trauma. The dynamic environment of the bending and stretching skin impacts on inflammatory responses.1 Cells exhibit an increased secretion of inflammatory cytokines when under mechanical stretch. I propose that strain dependent inflammatory responses cause pain in nipples. Stretch causes an influx of inflammatory cells and a cascade of signalling pathways. Pain is a warning.
At first, skin behaves like rubber in response to stretching forces, including from the stretching force which results from the vacuum inside a baby’s mouth during suckling.
Initially, skin stretches a great deal. But it becomes much stiffer at high stretch loads due to a cell-to-cell locking mechanism.2 The vacuum created inside the baby’s mouth by the drop of the jaw might stretch the epithelium until these locking bonds switch on. Then the nipple epithelium becomes much stiffer and resistant to the stretch.
The epidermis and dermis overlie the inner collagen-rich core of the nipple, which is also threaded through by nerve bundles. But if a high-enough stretching force is applied, a shearing load might arise between the epidermis and dermis and the more stable interior collagen structure of the nipple. Or the core and the epithelium may together experience a tissue deformation load. Histamine and inflammatory factors are released into the tissue, stimulating the nociceptors in the dermis which send messages to the brain, resulting in pain perception.
Graph Pawl 20131
Repetitive micro-trauma to the nipple and areola results from mechanical injury. the stretching force of a vacuum, when a high force is concentrated on a small area or the most vulnerable part of the tissue under stress. Mechanical injury includes compression forces, shear forces, deformative forces. Nipple damage is caused by mechanical load from stretching of the epidermis, which shears over the underlying collagen.
Pain is a sign of tissue injury, of stretching and shearing forces between the nipple skin (epidermis and dermis) and underlying collagen, which put the skin at risk of breaking. The shearing may cause inflammation and bruising (leakage of blood into deeper tissues). The more persistent the pain is, the more significant the microscopic damage from repetitive micro-trauma. The dynamic environment of the bending and stretching skin impacts on inflammatory responses.1 Cells exhibit an increased secretion of inflammatory cytokines when under mechanical stretch. Strain dependent inflammatory responses will cause pain in nipples. Stretch causes an influx of inflammatory cells and a cascade of signaling pathways. Pain is a warning. Don’t put up with it. For some it will go away, but for others it will simply get worse and worse if we don’t attend to it, and apply the strategies in this book.
You can find out about the mechanical effects of nipple and breast tissue drag on breastfeeding here.
VERSION 2
What causes nipple pain when there is no visible damage?
At first, skin behaves like rubber in response to stretching forces, and stretches a great deal. The nipple epidermis and dermis stretch in response to the mechanical force generated by the vacuum inside a baby’s mouth during suckling. But epithelium becomes much stiffer at high stretch loads due to a cell-to-cell locking mechanism.28 (see p 10 Functional anatomy ‘How does the skin respond to stretching forces?’)
Nipple pain results when the stretching forces aren’t evenly distributed over a large enough surface area of nipple and breast tissue inside the baby’s mouth, and the nipple is subject to bending or deformational forces. In these situations of breast tissue drag, the vacuum created inside the baby’s mouth by the drop of the jaw might stretch the epithelium until these locking bonds switch on, so that the nipple epithelium begins to resist the stretching forces. The epidermis and dermis overlie the inner collagen-rich, vascular core of the nipple, which is threaded through with nerve bundles. If a high-enough stretching force is applied, a shearing load might arise between the epidermis and dermis and the more stable interior collagen structure of the nipple. Or if there is breast tissue drag, the core and the skin of the nipple may experience a bending or deformation load.
If sufficient mechanical stretching and bending loads are applied to the nipple and surrounding breast tissue as the baby’s jaw drops and the baby sucks, the epidermis, dermis and deeper collagen cells of the nipple core release inflammatory cells and cytokines and histamine. This inflammatory response switches on a cascade of signalling pathways. Nociceptors are stimulated and send messages to the brain, resulting in the perception of pain. Shearing or bending deformational forces from the way the epithelium stretches differently to the collagen in the nipple core, may cause bruising, which is leakage of blood into deeper tissues, which results in inflammation without visible tissue damage. The more persistent the pain is, the more significant the microscopic damage from repetitive mechanical micro-trauma.29
Pain is a sign of tissue injury, of stretching and shearing and bending forces on the nipple skin (epidermis and dermis) and underlying collagen and nipple core, which put the skin at risk of breaking. Pain is a warning. Don’t put up with it. For some it will go away, but for others it will simply get worse if we don’t apply the strategies in this book.
References
1. Pawlaczyk M, Lelonkiewicz M, Wieczorowski M. Age-dependent biomechanical properties of the skin.* Postep Der Alergol*. 2013;5:302-306.
2. Tepole AB, Gosain AK, Kuhl E. Stretching skin: the physiological limit and beyond.* International Journal of Non Linear Mechanics*. 2012;47(8):938-949.
3. Ventura AK, Lore B, Mireles O. Associations between variations in breast anatomy and early breastfeeding challenges.* Journal of Human Lactation*. 2020:doi:10.117/10890334420931397.
4. Vazirinejad R, Darakhshan S, Esmaeili A, Hadadian S. The effect of maternal breast variations on neonatal weight gain in the first seven days of life.* International Breastfeeding Journal*. 2009;4(13).
5. McClellan HL, Kent JC, Hepworth AR, Hartmann PE, Geddes DT. Persistent nipple pain in breastfeeding mothers associated with abnormal infant tongue movement.* International Journal of Environmental Research and Public Health*. 2015;12:10833-10845.
- Zimmerman E, Thompson K. Clarifying nipple confusion.* Journal of Perinatology*. 2015;35(11):895-899. ↑