Tailor-made milk: the incredible process of breastfeeding

The ability of the female body to tailor make the perfect milk for baby is astounding. Lactation consultant and midwife, Stephanie Callaghan Armstrong unpacks the wonders of this incredible process.

The human breast is one of the great wonders of the world, in my opinion. Microscopic hormones released in puberty and during pregnancy from the brain, along with ovaries and adrenal glands, transform your breasts to become on-demand milk factories for your baby.

Sometimes when I truly try to grasp how milk is made, it blows my mind with how incredible it really is, and how the perfect milk is made for your baby. It primes baby’s gut in the first several days with colostrum and adjusts its composition uniquely to environmental factors like climate, altitude and even gestation, in the case of a premature baby.

STAGES OF LACTOGENESIS

Let’s explore the stages of lactogenesis 1, 2 and 3, otherwise known as the changes in your breasts to prepare them to make the perfect milk and supply for baby and to see how it all works inside your breasts in pregnancy, and after birth.

Your breasts are a type of gland, which basically means an organ in the body that produces a substance, in this case breast milk. Other examples of glands are tear ducts, sweat glands, hormone glands like the pituitary and adrenals and other glands that produce digestive juices for the gut.

When a young woman starts puberty, the hormones oestrogen and progesterone activate breast growth and changes within to grow the immature breast duct system she was born with.

As she goes through puberty, her breasts will grow and enlarge, a fat layer is laid down, and she may notice changes with her menstrual cycle, experience tenderness, and changes in size as those different hormone levels fluctuate – all preparing her breasts for if she chooses to have a baby.

When you conceive your baby, your breasts may be like your body’s sign post of what is happening inside of you hormonally. For so many women, tender breasts are the first tell-tale sign they are expecting, along with the HCG (human chorionic gonadotrophin) hormones causing other classic pregnancy signs like smell hypersensitivity, nausea and changes to taste.

I find it helpful to visualize the inside of breasts looking much like a tree. The branches (or ducts) are formed first with the trunk growing out from the nipple in a number of ducts. In pregnancy, the branches grow further and 'leaves' (the alveoli, or milk sacs) are formed by the influence of the hormones. These sacs are surrounded by myoepithelial (muscle cells) that contract to create milk. This process starts at around 16 weeks pregnant, and is called lactogenesis 1 and it continues until the mature milk comes ‘in’ on days 3-5 postpartum.

FIRST TRIMESTER

In the first trimester, many women find their breasts become extremely sensitive and painful to touch due to pregnancy hormonal effects. They enlarge due to the duct system growing, with the nipple area darkening. Inside your breasts, the alveoli with their milk secreting cells inside, are forming and getting ready to produce milk. Some women occasionally secrete colostrum from their nipples even in the first trimester!

You may notice your breast veins becoming more prominent as there is an increased blood supply to the area. Wearing a firm supportive bra will help keep your tender breasts comfortable.

SECOND TRIMESTER

In the second trimester, your breasts are actually able to produce milk in case your baby is born preterm. You may notice the tenderness decreasing but the nipples further enlarging and little bumps appearing on them. These are called Montgomery glands, and they produce a substance that keeps your nipples moist and protected when breastfeeding. It also has been said that a scent is secreted that attracts baby to encourage latching, feeding and bonding – amazing!

The areola of the nipple enlarges as this is the breast tissue baby takes into their mouth to compress the milk that travels up the ducts. It is also said that the nipple darkens to attract baby visually to latching on. Incredibly, if baby is born preterm, your milk composition is different to that if you give birth full term, which supports baby’s different nutritional, neurological and immunological needs. It has higher proteins, fats, salts, and antibodies and greatly reduces baby’s risk of developing a life-threatening condition in the gut called necrotizing enterocolitis. 

THIRD TRIMESTER

Towards the end of this trimester, many women start to leak colostrum as the prolactin hormone levels rise. It’s a great idea at this stage to express and freeze colostrum for baby. This is particularly beneficial if baby is higher risk for low blood sugars and may need extra top ups at birth, for example if you have gestational diabetes or a growth restricted baby. The hospital I deliver babies in gives out packs to hand-express into syringes for easier collection and storage. Prenatal expressing is usually recommended from 36 weeks onwards.

As full term approaches your breasts likely will enlarge more and will get increasingly tender. This is the best time to buy or have breastfeeding bras fitted for breastfeeding to ensure they fit after baby is born.

Some women will report very little breast changes in pregnancy (and even in puberty) and this can be indicative of a lack of breast duct and alveoli growth and may impact your milk supply. However some mamas who have small breasts and little noticeable change have enough milk to feed a village! Either way, it’s always good to talk to your lead maternity carer about breastfeeding expectations and goals so they are alerted to watch out for your milk supply being established after birth and correct early latching issues to optimise this. Low milk supply is another whole topic, but there is a lot that can be done for almost every new mum to be supported to produce milk, please do get help if you need it!

I always ask my pregnant mums-to-be whether their nipples ‘pop out’ or are flat or possibly even inverted. If the latter is picked up in pregnancy, it can make a huge difference to baby latching well in the breastfeeding initiation stages. If your nipples (or sometimes it’s just one) are flat or appear sunken in, you can encourage lengthening of the connective tissue that is shortened. Take your thumb and first finger and place on the areola and encourage the nipple to roll out. You can use nipple cream such as lanolin-based Purelan, which is very similar to the fatty substance secreted by the Montgomery glands to make it comfortable. Breast shells can also be worn to draw out nipples for a few hours a day as they form a gentle suction and also breast pumping may help as you approach your due date to pull out inverted or flat nipples. If you use a breast pump, watch that the expressing action doesn’t cause contractions or early labour by stimulating oxytocin hormone release; modify to do less if it does.

You may get stretch marks on your breasts, particularly in the third trimester, which is usually painless but can become itchy and sometimes red and sore from any sudden overstretching. A fatty cream like cocoa butter may help soothe them.

BIRTH

Immediate skin-to-skin with baby on your chest after birth is a very important first step to successful breastfeeding. Baby can hear your heartbeat and their stress hormones settle, as do your own, and baby can smell your unique smell and see the nipple. Not that we do this very often due to baby getting cold straight after birth, but watching videos of a baby doing the so-called primitive reflex ‘breast crawl’ up to the nipple and self latching always amazes me. Usually baby needs time to settle straight after birth and ideally delayed cord clamping takes place so baby gets the extra nourishing placental blood after birth, covered in warm towels. Baby feels safe hearing your familiar heartbeat and voice which reduces the stress hormone (cortisol) levels. A relaxed baby is best for an optimal first feed! Even if you need stitches, I leave baby skin-to-skin whenever possible, and it can be the perfect distraction for mum.

Colostrum should be ready and waiting in your breasts for your baby’s first feed and until the milk 'comes in'. Colostrum, in its usually small amounts, gives baby antibody-rich first feeds for the best start of immune protection. It also contains white blood cells, vitamin A (that’s what creates the gold colouring) and many other antibacterial properties. Baby’s gut is lined by the colostrum ingestion, which helps with maturing and preparing it to digest all the nutrition in the next milk that is to come.

After baby is born, hormones play a leading role in your milk production; with the delivery of the placenta causing the hormones oestrogen and progesterone from pregnancy to fall, and for prolactin and oxytocin to take over.

Prolactin levels rise and are greatly increased by breast stimulation when baby latches and expresses milk, and night feeds are when the prolactin is highest and milk production peaks. This is why it's super important that baby latches well in the early postpartum days. Do get assistance from a midwife or lactation consultant if you are unable to latch baby or are having difficulties. If possible, express in place of baby feeding if you are separated for any reason.

Oxytocin is released from the brain by the pituitary gland in response to the suckling stimulation in the form of ‘let downs’ where milk is ejected into the ducts from the milk buds. The great thing about oxytocin is it's also a ‘feel good' hormone. Oxytocin makes us feel relaxed and loved and can be a special experience for both of you when you breastfeed and bond.

POSTPARTUM (LACTOGENESIS 2)

Between days 3-5, your milk 'comes in’. ‘In’ can be an understatement for some new mums with the sudden changes in their breast size and the huge discomfort from the swelling. While the alveoli (milk sacs) fill with milk, the increase in size and discomfort are also due to inflammation from the increased blood flow to the area and a lymphatic drainage backlog which takes away fluid and waste from the breast. The best way to prevent engorgement is to latch baby correctly and feed regularly straight from birth. Reduce inflammation by massaging gently towards your armpits to encourage lymphatic flow and blood circulation. Lie on your back, or take a warm shower and massage with a natural oil.

Regularly feeding baby day and night, plus hand-expressing to soften if baby has difficulty latching due to the areola being tight and full, helps relieve discomfort from very full breasts. Your nipples are more likely to become damaged due to incorrect latching at this early stage than any other – Purelan and coconut oil can help soothe and heal them. I always say that your nipple tissue is similar to your lips. For sore cracked lips we apply moisture and that also helps heal nipples. Other remedies are paraffin gauze squares and sometimes treatment with a medicated cream to reduce inflammation and treat any bacteria or fungal infections that have gotten into the cracks. It’s important to get support to latch baby or to have a health professional assess your feeding and baby’s mouth for causes like tongue and lip tie, because nipple abrasions cause pain and can result in stress and can be the biggest reason a new mum reports wanting to give up breastfeeding. Broken areas in the nipple increase the risk of bacteria which can cause mastitis which is not fun. Massaging lumps gently while feeding, compresses with a warm flannel over the breasts before feeds and a cool one after, and a firm bra or binder for support can all help soften them. (It’s quite old fashioned to use binders, but I remember the relief as a young teen mum with my first baby and having the worst engorgement ever. You can google how to make one from cloth and safety pins, but just a firm support even with a sports bra is the key.) Cold cabbage leaves on the breasts for about 20 minutes (or I always joke until you start smelling like a coleslaw!) can also help soften them due to an apparent enzyme in the leaves, and the coolness helps soothe the increased heat from the inflammation. As your milk supply establishes with supply and demand, engorgement resolves and your breasts will soften and eventually only feel full if you are delayed with feeding or expressing them.

LACTOGENESIS 3

This stage kicks in by around day 10 when mature milk is established and your body has worked through the supply and demand process.  

It is the reason why those first few weeks are so important – you are literally programming and setting a blueprint for your milk supply needs. The World Health Organisation Code – 10 Steps To Successful Breast Feeding (The Code) – was put in place to encourage this. It includes only feeding your baby breast milk after being born as adding infant formula top ups can interfere with establishing a good milk supply (unless there is a medical reason of course) so expressed milk top ups are a baby friendly way of giving extra milk and encouraging a good milk supply. The Code also recommends not using teats and dummies as the different suckling action to the breast can confuse some babies. Keeping baby close by so you can see their waking cues and are able to breastfeed on demand is also key.

Support and education for new mums is another Code step, as it’s a big new skill to learn so please always ask if you need help. Most hospitals have a breastfeeding clinic you can book into, or private lactation consultants like myself are available for local support.

The WHO Code also recommends breastfeeding baby for two years if you can, or until baby naturally weans. That is your decision of course, based on individual preference and circumstances, and over this time your breasts will slowly reduce back to their pre-pregnant state (or a version of!).

WEANING/INVOLUTION

As you wean baby from breastfeeding with solids and eventually stop breastfeeding, the ‘involution’ process similarly reverses the process of lactogenesis 1. It is more beneficial for both your baby and your breasts to wean slowly, so there is a gradual breakdown of the milk buds and baby’s gut adjusts to their new diet, while still receiving the benefits of breast milk as you wean.

The ducts remain ready in waiting for another pregnancy, just like a winter tree waiting for its leaves in spring. This is why induced lactation for a mum wanting to breastfeed an adopted baby or re-lactate after weaning, is more successful for a mum who has been pregnant before.

There is so much that can be done with hormone therapy and expressing stimulation however, and even partial breast milk and breastfeeding (with the possibility of using feed lines with donor or formula milk) is very beneficial for you both.

If weaning takes place abruptly (the process can start by just missing a few feeds) there is a greater risk of developing mastitis and things can snowball. The milk composition changes and can become salty to taste for baby and they may refuse your milk suddenly. Some mums take medications to ‘dry up’ and aid the process if they need to rapidly wean.

Each baby you have will be a unique experience and I know personally, I feel so blessed to have had that time breastfeeding each of my four babies. With a few of them I had some initial challenges, even being a midwife and lactation consultant, but I have precious memories of my breastfeeding experiences once they were overcome! In pandemic times there is also the added assurance that breastfeeding has immunity and protection benefits. *If you're vaccinated against COVID-19 there is evidence that you can provide extra protection for your baby through antibodies in your breastmilk. Those antibodies are also passed to your baby in pregnancy. Incredible times.
Kia Kaha, lovely mums!

* Ministry of Health NZ, health.govt.nz

Stephanie Callaghan Armstrong is a mum of five, experienced LMC Midwife and Lactation consultant and runs a breast pump rental and sales business with her husband Dr Mikey from The Barn in Coatesville, babymed.co.nz. Find her on Instagram @babylove.midwife.life & @babymednz