How Is Breast Milk Produced?

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Motherhood is magical in multiple ways. It is wondrous the way your pregnant body prepares for months to produce milk and nourish the baby the moment he/ she comes out of your womb.

But how does the milk start flowing the moment your newborn suckles your nipples? How does your body produce the milk? The seemingly magical development actually works on the principles of science.

MomJunction tells you about one such fascinating phenomenon: how is breast milk made.

Anatomy Of The Breast

To understand the production of breast milk, you need to understand the anatomy of the breasts and how they function (1).

Image: Shutterstock

  • Each nipple has 15-20 tiny outlets for the milk ducts that carry milk from the lobules to the nipples.
  • The milk lobules produce milk within the breasts. They form clusters that are called lobes, and a healthy breast can contain about 12 to 20 such lobes (2).
  • The Montgomery glands or areolar glands are the sebaceous glands on the nipple that produce oil to lubricate it. The oil has anti-bacterial properties that keep the nipple clean and free of bacteria. It is also believed that the oil gives out a fragrance that helps the baby easily detect the nipple while breastfeeding.
  • You may notice your nipple and areola getting larger during pregnancy and throughout your lactation state. The color of the areola and nipple also gets darker. It is mainly to make it easier for the baby to see the nipple.

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[ Read: What Are The Advantages Of Breastfeeding? ]

The Beginning Of Milk Production

The body starts preparing for milk production right from the moment you conceive. Keep reading to know how.

Ovarian hormones influence breast size and shape: Ovaries produce the hormones progesterone and estrogen. These hormones have a significant influence on how your breasts appear and how the milk lobules within it function. When you ovulate, estrogen creates new branches of milk ducts, which will carry the milk from the lobes to the nipple.

Progesterone increases the size and number of milk lobules to prepare the breasts for the production of milk. The hormone also increases the supply of blood to the breasts. All this makes you experience fullness and tenderness of breasts during menses (3).

Your first milk production begins in the second trimester: The effects of progesterone and estrogen wear out if you do not get pregnant during the menstrual cycle. Otherwise, the effects of these hormones remain, and the body further prepares the breast for lactation. As your pregnancy progresses, the breasts continue to change.

The nipples, areola, and the areolar glands grow larger and become more prominent than ever. By the 16th week, the breasts begin the production of colostrum, otherwise known as the “first milk”.colostrum is rich in protein, and the body produces more than enough of it as you near full term, causing it to leak a little during late second trimester, although some mothers may never leak colostrum during pregnancy. This is also considered to be normal (4).

Breasts are ready for lactation by the end of pregnancy: By the end of your pregnancy, the milk lobules inside the breasts are capable of handling round-the-clock milk production typically50-73 hours or 3 to 5 days after delivery of the baby and placenta.

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How Is Breast Milk Produced?

Once the baby has ingested the colostrum, the breasts will produce the first batch of milk. The following are the steps involved in the production of milk after the birth of your baby:

[ Read: What Foods Help To Produce Breast Milk? ]

1. Prolactin takes over:

  • After delivery, there is a drop of the hormones in the body since the uterus shrinks and the placenta is removed. Then, the hormone prolactin, which is produced by the pituitary gland inside the brain, takes over the milk production (5) (6).
  • Breast milk is fundamentally water, proteins, sugars, micronutrients, and antibodies. Prolactin stimulates the milk lobules to source these building blocks of milk from blood vessels. Once the milk lobes obtain these building blocks, they combine it all through a complex biochemical process to create milk. Prolactin ensures that both the breasts produce milk.
  • The effects of prolactin kick in about three to five days after the birth of the baby. By this time, your baby would have drunk all the colostrum, and prolactin would have stimulated the milk lobules to produce a fresh batch of milk.

2. The milk let down:

  • While prolactin stimulates the milk lobules, the hormone oxytocin is responsible for letting out the milk from the lobes into the ducts from where they can flow out through the nipple.
  • Oxytocin is produced in the hypothalamus region of the brain, which is close to the pituitary gland that produces prolactin (7).
  • Oxytocin makes the milk lobes contract and releases the milk into the milk ducts, from where it passes through the nipple. It is the milk ejection or let-down reflex that causes your body to push the milk to the nipple when your baby suckles to feed. Some mothers can feel a tingling sensation with their milk let down. Others do not ever feel it, but hear their infant starting to swallow actively. There is more than one let-down in a breastfeeding session, although it may or may not be noticeable to the mother.

3. Suckling stimulates more milk production:

  • Constant stimulus from your baby’s suckling and emptying of the breast enable prolactin and oxytocin to work towards production and let-down of milk respectively.
  • Other factors such as the baby’s crying or cuddling the baby skin to skin – may help trigger the let-down reflex.
  • Over a period, when the baby relies less and less on breast milk, the brain senses that the breasts are emptied less often than before. This brings down the production of breast milk and limits it to only as much your baby drinks. In other words, “Supply=Demand.”

When you are healthy, milk production goes on smoothly. Sometimes, there could be trouble producing the necessary amount of milk for various reasons. This is when you should always seek the help of a Board Certified Lactation Consultant, if available.

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[ Read: Plugged Ducts While Breastfeeding ]

Can There Be Problems In Milk Production?

Yes, you may experience problems with the production or the let-down of the milk due to the below reasons:

  1. Fatigue: The days after childbirth are perhaps the most stressful for a mother. Fatigue and stress can interfere with the production of oxytocin and may slow down the let-down reflex. Sharing baby duties with your partner and taking some time to rest are the best ways to prevent the onset of fatigue.
  1. Painful distractions, such as uterus cramps: Oxytocin also causes the uterus to contract after childbirth. This is good, because it prevents the mother from bleeding too much after delivery. However, The contractions can cause uterine cramps that could be distracting and may interfere with your ability to feed your baby in peace. The cramps will subside as the uterus gradually attains its regular shape and you will start feeling better.
  1. Rapid, unrelieved breast engorgement: Engorgement of breasts 3-5 days after delivery can make feeding painful. However, the breasts become less engorged as you feed the baby, creating an outlet for the milk to flow out.
  1. Poor latch and inability to feed: If the baby has difficulty latching to the nipple, then they may not get sufficient milk. It keeps the breast full, which in turn could signal the brain to reduce the production of prolactin, which eventually brings down the milk supply.

Listen to the suckling and swallowing sounds to know your baby is feeding. Look for a calm place to feed the baby. Stay relaxed while feeding for a better let-down reflex. Feel for a softer breast and look for your baby to be relaxed and satisfied when feeding is finished.

Read on for tips on how to prepare for breastfeeding.

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How To Prepare Breasts For Feeding?

Relaxing usually alleviates any problems caused during milk production and let-down. The following techniques may also help you achieve let-down (8):

  • Take a warm shower: A warm shower allows you to relax, to stimulate the production of oxytocin that enables easier milk flow from the nipple.
  • Wrap the breasts in a warm towel: Place a towel soaked in warm water on your breasts for a few minutes before feeding. It has the same effect as a warm shower.
  • Massage the breasts: It will stimulate milk flow from the lobes towards the nipple.
  • Relaxation through other methods: Listening to soothing music, going for a walk or taking a nap are some of the ways to feel calm and less stressed before the breastfeeding session.

[ Read: How To Express Breast Milk By Hand ]

The body works round the clock to produce milk for your baby and to ensure that there is enough for it as long as the little one wants to feed. Eat healthy foods and maintain hygiene to ensure your baby gets as much breast milk as needed. If you face problems with breastfeeding, see a lactation consultant to get your doubts cleared.

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Do you have any experiences to share? Tell us about them in the comments section.


MomJunction's articles are written after analyzing the research works of expert authors and institutions. Our references consist of resources established by authorities in their respective fields. You can learn more about the authenticity of the information we present in our editorial policy.
1. Breast Milk Production; Sutter Health Network
2. Breast Anatomy; National Breast Cancer Foundation
3. Breast Anatomy;Cleveland Clinic
4. Changes in the breasts; The Open University
5. Reviewed by L Adler, D Freeborn; How Breastmilk is Made; University of Rochester
6. Reviewed by D Zieve, I Ogilvie et al.; Prolactin blood test; US National Library of Medicine, Medline Plus
7. S K Fineberg, D A Ross; Oxytocin and the Social Brain; Biol Psychiatry (2017)
8. Ten Valuable Tips for Successful Breastfeeding; Government of Canada

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Jill Lancaster

(RN and IBCLC)
Jill Lancaster from Springville, Utah, graduated from Brigham Young University College of Nursing with BSN in 1997. She has worked as a Registered Nurse and an International Board Certified Lactation Consultant (IBCLC) and has more than 21 years of experience working with breastfeeding mothers and babies. She has extensive experience in hospitals, outpatient clinics, and now runs her own private... more

Swati Patwal

Swati Patwal is a clinical nutritionist and toddler mom with over eight years of experience in diverse fields of nutrition. She started her career as a CSR project coordinator for a healthy eating and active lifestyle project catering to school children. Then she worked as a nutrition faculty and clinical nutrition coach in different organizations. Her interest in scientific writing... more