How is breast milk "produced"?

This is an automatically translated article.

This article is professionally consulted by Master, Doctor Nguyen Nhu Thu Truc - Obstetrician and Gynecologist - Department of Obstetrics and Gynecology - Vinmec Nha Trang International General Hospital. Doctor has more than 8 years of experience in the field of Obstetrics and Gynecology.
In most cases, breast milk will be produced based on the actual needs of the baby. The more often and efficiently your baby suckles, the more milk your body makes.

1. Anatomy of the breast

Breast structure consists of 3 main tissues: glandular tissue, adipose tissue and connective tissue. Mammary glands of mothers can be different in size depending on the composition of fat and connective tissue more or less. The amount of breast tissue is almost the same.
From the outside to the inside, the breast consists of 5 layers: skin, subcutaneous fat and connective tissue, cooper ligaments suspending the breast, glandular tissue and posterior glandular tissue. The glandular tissue is divided into 15-20 lobes, arranged in a spokes shape, focusing on the nipple. Each lobe consists of 38-80 lobules and each lobule has many milk follicles.

Milk will from the lobules pour into the collecting ducts in each lobe (about 2mm in diameter) and then go to the milk-filled sinuses under the areola (with a diameter of 5-8mm). There are a total of 5 - 10 milk ducts open at the nipple. Also due to the special structure of the mammary gland, milk duct obstruction can occur in one or more milk follicles, one or more lobules and one or more lobes of the mammary gland.

2. Breast milk production time

During pregnancy, a mother's breasts get ready to produce milk. Colostrum is produced by the mother's body from the second trimester of pregnancy until about 2-4 days after the baby is born. Colostrum is characterized by light yellow or clear, sticky consistency, rich in nutrients and antibodies. Colostrum contains more protein than mature milk. It is very important for babies to receive colostrum in the first feedings, especially in the first hour after birth. Colostrum is already present in the breast soon after the baby is born.
After the baby is born, the placenta is shed, the mother's body begins to produce more milk. After about 5-14 days after the baby is born, the mother's body produces transitional milk. From day 14 onwards, the amount of milk secreted by the mother's body will continue to increase, turn white and thinner, called mature milk. More milk makes the mother's breasts full and firm. It is called the phenomenon of “milking”.

Foremilk: is the milk secreted at the beginning of a feeding. Foremilk has a greenish color, is large in quantity and provides a lot of protein, sugar, water and other nutrients.
Milk at the end of the meal: Is the milk secreted at the end of a baby's feeding. The mother's breasts are now full. The milk at the end of the meal is white because it contains more fat than the milk for the first time. Fat provides a lot of energy for the baby to help the baby grow faster, so it is important to let the baby finish the milk, not let the baby release the breast early or switch sides too soon.

3. How does the body produce breast milk?

Breast milk production is influenced by four hormones: estrogen, progesterone, prolactin, and oxytocin. The body's mechanism of producing breast milk is to self-regulate the levels of these hormones to produce milk. Specifically:
Estrogen and Progesterone help develop breasts, ready for milk production. These two hormones are released by the placenta during pregnancy. Estrogen is responsible for increasing the size and number of milk ducts, while progesterone helps in the development of follicles and lobules of the milk glands. High levels of estrogen and progesterone inhibit milk production while the baby is in the womb. When the baby is born, the placenta has shed, the levels of these hormones automatically decrease, telling the body that it is time to make milk. Also, nursing mothers should not take birth control pills containing estrogen because it will reduce the amount of breast milk. Prolactin helps produce milk. (lactation reflex) When the baby sucks on the breast, it stimulates the secretion of Porlactin. Prolactin enters the bloodstream, reaches the breast, and causes the breast to produce milk. Most prolactin stays in the blood for about 30 minutes after a feed, so it helps make milk for the next feed. This shows that if the baby suckles a lot, the breast produces more milk. Prolactin is produced more at night which is very helpful to maintain milk production.

Oxytocin releases milk from the breasts. The hormone oxytocin is released when the baby begins to pull on the nipple and suck. Oxytocin contracts the muscles around the follicle, pushing milk out of the follicle, into the milk ducts, moving to the nipple, and into the baby's mouth. This process is called the milk ejection reflex. If the oxytocin reflex is not working properly, the baby will have difficulty receiving milk, although the breast is still producing milk but not ejecting it. The milk ejection reflex is easily influenced by the mother's thoughts. When a mother has good feelings such as being satisfied with her baby, close, loving her baby, always believing in breastfeeding, it will support this reflex well. In addition to releasing milk from the breasts, oxytocin also helps to contract the uterine muscles during and after childbirth, helping the uterus shrink to its original size and limit postpartum bleeding. At the same time, prolactin and oxytocin also contribute to the mother's desire to be with her baby.
The lactation reflex may occur several times during each feeding, and the mother may feel tingling, slight discomfort in the breasts, or no other sensations. This reflex can also occur when the mother hears her baby cry or thinks about her.
Inhibition of lactation: in breast milk there is a secondary factor called lactation inhibitor. When a large amount of milk is deposited in the breast, an inhibitor is released that stops the breast from making milk. Therefore, in order for the breast to produce more milk, it is necessary to make the breast always empty by feeding the baby often or expressing milk.

4. How to make a mother have enough milk for her baby

When your baby breastfeeds, the stimulation from the baby's sucking action helps the mother release more prolactin hormone which helps the mother's body to produce more milk. This mechanism helps the mother always have enough milk for the next feeding. So, the more often a mother breastfeeds properly, the more prolactin she will have in her blood and the more milk she will produce.
According to doctors, women should breastfeed or pump milk within 1 hour after giving birth, feed the baby every 2.5 - 3 hours.
Mothers need to rest, relax and eat enough nutrients; Always keep an optimistic spirit, believe that breastfeeding will bring abundant milk for the baby.

Breast milk contains a special protein, called a feedback inhibitor of lactation (FIL). This protein determines how much milk each breast will produce. If a mother breastfeeds her baby from each breast regularly, the level of FIL in the breast will be low. Low levels of FIL stimulate the body to produce more milk. Therefore, you should let your baby drain from each breast before switching sides.
FIL determines the amount of milk in each breast separately. That means that one breast may be low on milk, but the other breast may have enough. So, even if a mother has a blocked milk duct on one breast, she can still breastfeed her baby from the other breast, and mothers of twins can still breastfeed exclusively.

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