How Breastfeeding Works

Anatomy of the Female Breast

Each nipple has 15 to 20 lobes of milk making glandular tissue, made up of clusters of alveoli. From these lobes run special channels called ducts which form into sinuses beneath the areola . From here the milk can flow out of the openings in the nipple . The nipple and areola (the dark area around the nipple) get bigger and darker during pregnancy.

On the areola there are small bumps called Montgomery Glands . These produce a natural oil which cleans, lubricates, and protects the nipple during pregnancy and breastfeeding. This oil contains an enzyme that kills bacteria. So no need for protective creams, lotions and potions ladies, it’s there already. The best way to keep this wonderful natural protection is to wash the breast with water only and take care while drying, don’t rub the nipples, pat them dry.

The breast consists mostly of connective and fatty tissues that support and protect the milk producing areas of the breast. The milk is produced in small clusters of cells, called alveoli and travels down milk ducts to the milk sinuses, which collect and store the milk until it is needed. These sinuses are located behind the areola.

When your baby begins to breastfeed, the nipple is drawn back into the back of the mouth and is held there by suction so that the sinuses are between the upper and lower jaw. The action of the tongue and jaw squeeze the sinuses forcing the milk into the baby’s mouth.

The tongue should lie over the bottom gum. The further back into the baby’s mouth the nipple is, the less likely it is to cause pain or discomfort. You can test this effect yourself. Try sucking on your own thumb, the deeper the thumb goes into the mouth, the more comfortable it feels.

The key concepts of breastfeeding

There are two key concepts which every breastfeeding mother needs to know in order to establish a good milk supply and to understand how to work through potential difficulties. These are ‘supply and demand’ and ‘the let-down reflex’.


This is simple. The more milk the baby takes from the breast, the more milk you make.

If you feel that your baby is hungrier than usual, feed more often. Your baby may need a top up feed at the breast if it does not settle after a breast feed or wakes up frequently. Feeding according to your baby’s need will establish a good supply of milk that will suit your baby’s needs perfectly.

As you get through the early weeks, your breasts will not feel as full as they were when your baby was first born. This does not mean that you don’t have a good supply, it is usually just a sign that your breasts are more used to breastfeeding, your supply is well adjusted and the whole process is happening very efficiently. Many mothers notice their breasts feel softer again around the 6-8 week mark. This is often when breastfeeding becomes the enjoyable, comfortable experience you have heard rumours about.

The Let-Down Reflex

This is your body’s response to the baby’s suckling and is responsible for squeezing the milk from the alveoli into the ducts and towards the nipple. Sometimes it causes the milk to drip or even squirt from the nipple.

How does it work?

Your baby’s suckling stimulates the nerve endings in the nipple and areola, which tells the pituitary gland in the brain to release two hormones, prolactin and oxytocin.

  • Prolactin causes your alveoli to take nutrients (proteins, sugars) from your blood supply and turn them into breast milk.
  • Oxytocin causes the cells around the alveoli to contract and force the milk down the milk ducts. This is also the hormone responsible for contractions in labour and after the birth. The contractions after birth help your uterus to return to its pre-birth shape and size and tend to get more painful the more children you have. These after pains mostly come on while breastfeeding for the first 24-48 hours after delivery.

There may be many let-downs during a breastfeed although you may not feel them all. Most mothers only notice the first one. The others occur in response to changes in the baby’s sucking rhythm.

The brain plays a large role in the release of hormones that cause the milk to eject so it is very normal for let-downs to occur in other situations as well. You might notice a let-down when you think its feeding time, when you think about your baby, hear your baby or even hear somebody else’s baby cry.

Some mothers may notice a let down when sexually aroused or even during orgasm. This is because oxytocin is also a bonding hormone and is the major hormone involved in orgasm.

How do I know I have had a let-down?

  • Your baby will begin to rapidly suck and swallow rhythmically
  • Milk may drip from the opposite breast
  • You may feel a tingling or a full sensation in the breasts
  • You may feel thirsty

Encouraging the let-down reflex

  • Try to be as relaxed and comfortable as possible. Some mothers find it helpful to unplug the phone, turn on relaxing music, and take a few deep breaths
  • Sit in a comfortable chair with good support for your arms and back. Many mothers find that rocking chairs work well
  • Make sure your baby is in a comfortable position on your breast. Correct positioning is one of the most important factors in successful breastfeeding
  • You can try to listen to soothing music and sip a nutritious drink during feedings
  • If your household is very busy, set aside a quiet place ahead of time where you will not be disturbed while breastfeeding
  • Sometimes just thinking about your baby, hearing baby cry or stroking their hair will cause a let down
  • You can often train your self to have a let down by sitting in the same chair, listening to the same music or following the same routine every time you breastfeed
  • If you have trouble encouraging the let down, you can try gently massaging the breast before the feed or apply a warm towel or heat pack

What can interfere with the let-down reflex?

  • Emotions: embarrassment, anger, irritation, fear or resentment
  • Tiredness
  • Inadequate sucking this can be because of improper positioning or because the baby has not been at the breast for long enough
  • Stress
  • Fear of pain in your breasts or uterus (i.e. sore nipples or afterbirth pains)
  • Engorgement in the first few days
  • Smoking, alcohol or recreational drugs. These all contain substances that can interfere with the let-down and affect the content of breast milk

The different types of breast milk

Colostrum is the early milk made by your breasts, and is often noticed after the fifth or sixth month of pregnancy. Once the baby is born, it is present in small amounts for the first 3 days to match the small size of the baby’s stomach. To establish a good supply and to ensure that your baby gets plenty of Colostrum it is best if you can begin breastfeeding as soon as possible after giving birth and every 1 to 3 hours after that or when ever you baby is awake and happy to feed.

Colostrum is designed to meet the special needs of a newborn. It has a yellow colour, is thick in consistency, is high in protein, and low in fat and sugar. The protein content is three times higher than mature milk because it is rich in the immune factors being passed from the mother to protect the baby, like an all in one immunisation. It also acts as a natural laxative, helping the baby pass the first stools called meconium which is typically blackish in colour.

Mature Milk

A few days after your baby’s birth, your ‘milk will come in’. This refers to the time when your breasts start making mature milk and reduce the amount of colostrum they produce. Breast milk is made of fats, sugars, proteins, minerals, vitamins, and enzymes and is designed to promote brain and body growth. Antibodies are also present in your breast milk, which help boost your baby’s ability to resist infection. As your baby grows older, your milk changes to meet your baby’s individual nutritional needs.

Do you have questions about breastfeeding? You can ask Julie here. Why not get a 7 day guest pass to Natural Transition’s members resources and listen to the ‘Everything you need to know about Breastfeeding’ interview.

4 thoughts on “How Breastfeeding Works

  1. So Julie Cottle, are you the author of this? until i read the comments I could not find an author….

    1. Hi Gabrielle, yes, I am the author of all articles on the site with the exception of a few that have other author attributions on the articles themselves. If you’d like to use any of my articles, let me know 🙂
      With thanks,


  2. Hi there, my question with regards to breast feeding is how food gets turned into milk…. ie. when I eat something at what point of digestion does it go to my baby?


    1. Thanks for your question Christina, sorry I didn’t answer it sooner, I missed it!
      When you eat something, your body completely metabolises it as normal and the nutrients are absorbed into blood stream as they are when you are not breastfeeding. The breastmilk is made in the breast and the nutrients and components that make up that milk are absorbed from the bloodstream. Some things that you ingest do not pass into the breast milk, some pass into it quickly and other more slowly. It can take anywhere from 1 hour to 24 hours for a particular substance to pass from the mothers digestive system into the breastmilk depending on what it is. Does that answer your question?

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