Some Interesting Facts About Breastfeeding


Size Doesn’t Matter

Breasts are made up of two different types of tissue: adipose and glandular tissues.

Adipose tissue is commonly known as body fat and determines the size of your breasts.

Glandular tissue is where the magic happens.

Milk is produced and stored in the glandular tissue. Milk is synthesized in small structures called alveoli, which form milk lobules that connect to milk ducts that transport milk to the nipple.

A 2005 study concluded that the proportion of glandular and fatty tissue, and the number and size of ducts didn’t affect milk production [1].

(* There is a condition called Insufficient Glandular Tissue (IGT) or breast hypoplasia. These breasts usually have quite a distinguished shape which a good lactation consultant will be able to spot.)




Milks storage capacity if different for different women

The breast’s storage capacity can vary significantly among women, ranging from 74 to 382 mL, with an average of around 180 mL [2].

When there is more milk stored in the breast available to the infant, it typically results in the infant receiving a larger volume of milk. Consequently, women with smaller storage capacities may find it necessary to feed their infants more frequently compared to those with larger storage capacities. But over 24 hours, all babies will take about the same amount regardless of whether they are drinking from breasts with large or small storage capacity.

The daily milk intake remains fairly consistent from 1 to 6 months of age. Milk production is primarily driven by your baby’s needs, and there isn’t a direct correlation between the amount of glandular tissue and milk production or storage capacity.

This is why it is important to work with the breasts you and your baby have rather than having a one-size-fits-all timing schedule for breastfed babies.

Babies may feed anywhere between 8-12 times in 24 hours, with each feed varying in length. Some mothers may offer one breast per feed, while others may need to offer both breasts, and this can change from feed to feed. There is no need to watch the clock; instead, offer the breast whenever the baby cues for it. Breastfed babies cannot be overfed, and each mother-baby pair has their own unique breastfeeding pattern.

Glandular Tissue is not Uniformly Spaced Around the Breast

Our understanding of the structure of a lactating breast comes from the work of Sir Astley Paston Cooper’s ‘Anatomy of the Breast,’ published in 1840. It turns out that he was quite a Type A personality, and he untwisted the glandular tissue, stretched it out, and arranged it in a very ordered pattern. However, much more recent ultrasound studies have shown that the ducts are intertwined and quite bunched up with 65% of the glandular tissue is located within 3 cm from the nipple [1].

This study also found that the ducts are easily compressed, which has led to new recommendations around avoiding anything that will compress them and therefore inflame the ducts, such as certain “holds” during breastfeeding, breast shields, tight clothing, and deep massage. It is important to be very gentle with your breasts, especially within 3 cm of the nipple.

This also has implication for where it is easier for you to hand express. As with everything else, this can vary between women.

By the way there is also new thinking around mastitis with up to date lactation professional no longer referring to “block ducts” but that is another blog.



The First Few Days Are Critical 

Your milk production is triggered when progesterone levels decline following the delivery of the placenta. But milk production also relies on frequent milk (colostrum) removal from the breast. Inadequate breast emptying can diminish milk production. Aim for 10 milk (colostrum) removals in the first 24 hours after birth. Hopefully, this will be your baby doing the work, but if for any reason they can’t, then you need to hand express.

The initial days following birth are vital for kickstarting milk production. Regular feeding prompts the release of prolactin, initiating milk production. Frequent feeding also offers advantages to the infant, such as preventing low blood sugar, excessive weight loss, and jaundice. The success of breastfeeding hinges on the baby’s effective and frequent suckling, in the first 2 weeks

It’s All About the Vacuum, Not the Tongue

As I said before, our understanding of breastfeeding comes from Sir Astley Paston Cooper’s work published in 1840. However, he got something very wrong. In his studies (pouring hot wax through the glandular tissue of dissected lactating breasts), he found that the ducts widened behind the nipple and formed “lactiferous sinuses.” It was thought that the milk pooled in these sinuses, and that the baby had to use its tongue to “strip” the milk from these sinuses.

This theory was blown away in 2005 when Donna Geddes (nee Ramsay), while ultrasound scanning live lactating breasts, discovered that the “sinuses” Cooper saw were not there. It is now believed that the hot wax pooling created these sinuses and they are not part of a normal lactating breast.

With this discovery, the whole biomechanics of breastfeeding needed to be reexamined. Geddes and her team found that effective milk removal relies on the baby creating the appropriate vacuum, not the “peristaltic action” of the tongue [5].

During effective milk removal, the baby forms a secure seal with the breast, creating a vacuum with its lower face pressed against the breast. As the baby lowers its jaw and tongue in unison, a vacuum is created, and the milk flows into the baby’s mouth, assisted by a letdown reflex. Efficient milk removal is accomplished by positioning the baby with a deep, snug attachment of their face to the breast and ensuring symmetric placement around the nipple/areola area.

If there is positional instability or asymmetry as the vacuum is created and during feeding, this can cause excessive breast tissue drag, resulting in nipple pain and damage [6].

Knowledge is Power

Because not all those involved in supporting breastfeeding are up to date with the latest research, I highly recommend attending my Prenatal Breastfeeding workshops. The first few hours and days are so important. If you understand the biomechanics of breastfeeding and the principles of milk production, you can get your breastfeeding journey off to the best start.

It will also help you navigate all the coflicting advise most women receive on breastfeeding i n the first few days.

Additionally, make sure you seek help sooner rather than later, as milk production levels are established early. You want to ensure you have set yours at the optimal level for your baby’s needs.




[1] DT Ramsay, JC Kent, RA Hartmann, PE Hartmann. “Anatomy of the lactating human breast redefined with ultrasound imaging.” J Anat. 2005 Jun; 206(6); 525-534

[2] DT Geddes ,  Z Gridneva ,  SLPerrella , LR Mitoulas, JC Kent , LF Stinson , CT Lai , V Sakalidis , AJ Twigger , PE Hartmann . 25 Years of Research in Human Lactation: From Discovery to Translation. Nutrients. 2021 Aug 31;13(9):3071.

[3] K Uvnäs Moberg ,  D K Prime  Oxytocin effects in mothers and infants during breastfeeding. Infant 2013; 9(6): 201-06

[4] K Uvnäs Moberg , A Ekström-Bergström , S Buckley ,  C Massarotti,  Z Pajalic,  K Luegmair, A  Kotlowska, L Lengler, I Olza, S Grylka-Baeschlin, P Leahy-Warren, E Hadjigeorgiu, S Villarmea, A Dencker. Maternal plasma levels of oxytocin during breastfeeding-A systematic review. PLoS One. 2020 Aug 5;15(8):e0235806. doi: 10.1371

[5] Dt Geddes, VS Sakalidis, AR Hepworth, HL McClellan, JC Kent, CT Lai, PE Hartmann. Tongue movement and intra-oral vacuum of term infants during breastfeeding and feeding from an experimental teat that released milk under vacuum only. Early Hum. Dev. 2012, 88, 443–449

[6] P Douglas. Re-thinking lactation-related nipple pain and damage. Women’s Health. 2022;18.

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