The shape of women's breasts and nipple-areolar complexes comprise a glorious spectrum of anatomic trait variation. So do certain maternal anatomic variations cause breastfeeding difficulties?

Maternal breast and nipple-areolar complex anatomy are on spectrums of normal human anatomic trait variation

Anatomical variation encompasses the spectrum of structural differences observed within the human body, influencing organ morphology, tissue composition, and physiological function.

The shape of a woman's breast and nipple-areolar complex (NAC) lies somewhere on the gloriously broad spectrum of human anatomic trait variation, usually associated with normal function. Some breast and NAC anatomic variants on the spectrum of trait variation may be more likely to be associated with impaired function. One example at the extreme end of the spectrum of variations is referred to as mammary hypoplasia.

The relationship between breast and NAC shape and capacity to directly breastfeed or produce enough milk to exclusively meet an infant's caloric needs is unpredictable, including in the case of mammary hypoplasia. This is because the breastfeeding mother and her baby form a complex biological system, with multiple anatomic factors interacting all at once, and compensating for each other. Every mother has the right to state-of-the-art clinical breastfeeding and lactation support, to optimise her milk production and her capacity to directly breastfeed if this is her desire, regardless of her biological traits.

Some studies have linked certain (poorly defined) maternal anatomic variations with breastfeeding problems

It’s true that certain poorly defined anatomic variations have been shown in some preliminary studies to link with breastfeeding problems, including nipple pain.

• A 2009 Iranian study showed that 50 newborns to mothers who presented with a flat nipple, inverted nipple, large breast and/or large nipple did not increase in mean weight (or had a mean decrease in weight) by day seven compared to 50 newborns whose mothers did not have these breast variations.

• A 2013 Thai study showed that nipple lengths of less than 7 mm were less likely to initiate breastfeeding in the first 24 hours. Smaller breast size and longer nipple lengths were associated with longer breastfeeding durations.

• A 2017 Brazilian systematic review into factors associated with nipple pain found a link between nipple pain and "semi-protruding and/or malformed nipples", in the absence of any further clarifying definitions. (The term "malformed nipple"s does not refer to normal anatomic variation, but to congenital abnormality.)

• A 2020 study of 119 participants at a Californian breastfeeding centre showed that various combinations of wider, longer nipples and denser areolas were associated with difficulty latching, sore nipples, low milk supply and slow infant weight gain.

A breastfeeding atlas which is commonly recommended as a resource for lactation consultants speculates that larger breasts, shorter and wider nipples, and denser areolas (determined by gentle squeezing at base of nipple to test elasticity) disproportionately cause early breastfeeding challenges. This claim is not based on research, but upon the author's clinical experience. For example, we don't know the approach to fit and hold typically used by the author when working with breastfeeding women.

This research listed above and the clinical anecdote in the atlas emphasise just how important it is for breastfeedingwomen to have education about the strategies which will help to eliminate breast tissue drag and have the baby draw up as much breast tissue as possible into his mouth, regardless of anatomic variability.

It is possible that the psychological effects of pathologising normal anatomic variation is a more powerful cause of breastfeeding distress and failure than the variations themselves

In my view, pathologising anatomic diversity and blaming the mother or baby’s otherwise healthy body is a compensation for our lack of effective tools for clinical breastfeeding support, in particular with respect to fit and hold. This is no individual practitioner’s fault, but arises out of our history of a relative a lack of investment in clinical breastfeeding and lactation research. For example

• Healthcare challenges specifically relevant to women's bodies have not been prioritised in research.

• Breastfeeding problems have been seen as 'soft' concerns. (At least the woman and her baby are alive and well, doctors have often said!)

Also, there are powerful ideological forces at work within breastfeeding and lactation advocacy networks which aim, through social media use and active exclusion of certain new work from networks and conferences, to silence researchers and clinicians who contest dominant, pathologising paradigms in this field.

It is possible that the psychological effects of pathologising normal anatomic variation (and the failure to look for other solutions) is a more powerful cause of breastfeeding distress and failure to explore potentially helpful interventions, than the effect of the anatomic variations themselves. This effect would need to be controlled for in randomised controlled trials.

Selected references

Dias JS, Vieira TDO, Vierira GO. Factors associated to nipple trauma in lactation period: a systematic review. Revista Brasileira de Saude Materno Infantil. 2017;17(1):27-42.

Hendry P. Anatomical variation exploring diversity causes and clinical relevance. International Journal of Anatomic Variations. 2024;17(6):601-602.

Mizrachi B. Unraveling the spectrum of variation in human anatomy insights from genetics, development, and evolution. International Journal of Anatomic Variations. 2024;17(2):520-521.

Puapornpong P, Paritakul P, Suksamarnwong, Srisuwan S, Ketsuwan S. Nipple pain incidence, the predisposing factors, the recovery period after care management, and the exclusive breastfeeding outcome. Breastfeeding Medicine. 2017;12:169-173.

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).

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.

Wilson-clay and Hoover 2017. The breastfeeding atlas (6th edition), LactNews Press.