Stages of Lactation

What is lactation? Lactation happens when the mammary glands in the breasts of a mother (mammal), produce milk for her infant.

All female mammals have mammary glands to feed their young. The word “mammary” is derived from the Latin word “mammae” which is a sound similar to the sound made when a baby is rooting/searching for the breast.


What are the different stages in lactation?

1. Mammogenesis: This is when the breasts are developed, right from birth, through to puberty and then the process is completed during pregnancy.

This stage of lactation, starts in a woman when she is still in her own mother’s womb, as a small embryo. At 12 weeks gestation, the breasts have developed nipples, areolae, alveoli (milk producing cells) and mammary buds.

Sex hormones will then further develop the breasts until she is born.
During puberty, Estrogen and pituitary growth factors will cause the breasts to grow. New breast tissue is accumulated with every monthly ovulation cycle, up until the age of 35.

A woman’s breasts, are only ready to produce milk once she has become pregnant, this is when the final changes in the breasts occur to enable her to produce milk. The hormones responsible for these changes during pregnancy include: Prolactin, Placental lactogen, Estrogen, Progesterone, and the Adrenocorticotropic hormone.

Read more on hormones responsible for lactation.

So what changes occur during pregnancy?

* A web of milk ducts, spread and grow within the breast.
* The areolae and Montgomery's tubercles grow larger.
* The nipples become more prominent.

 The Anatomy of the Breast
Each breast contains about 20 lobes of glandular tissue (they look like little trees) The “leaves” of these trees are made up of alveoli, which are the milk producing cells. The milk flows from the alveoli to the ductules and then into the ducts and then finally out the nipple through duct openings.
The breast also contains many blood and nerve vessels as well as lymph vessels.
Read more on the anatomy of the lactating breast.

2. Lactogenesis: (creation of milk) (stages 1 and 2) This is when a Mom starts to actually produce milk. Stage 1 is between mid pregnancy and two days postpartum (after the birth). Stage 2 is between day 3 and day 8 postpartum.

Lactogenesis stage 1 and 2 are controlled by hormones.

In stage 1, Mom's breasts may feel swollen; this is because of the alveoli that have started to produce colostrum.

In stage 2 the alveoli cells become closed and tightly spaced. This increases the production of lactose, glucose and milk lipids and decreases the production of protein, sodium, chloride, nitrogen and magnesium.

During this stage, the breasts may feel warm and become engorged, if they are not breastfeeding frequently enough. If the Mom, does not breastfeed, her breasts will stop producing mature milk and start producing colostrum again, and then finally stop producing milk all together. The breasts will start to produce colostrum after three days of no milk removal from them.

3. Lactogenesis stage 3: Also called galactopoiesis. This is the production and maintenance of mature milk from day 9 postpartum until Mom and baby decide to wean.

Lactogenesis stage 3 is controlled by the endocrine system, but hormones do still play a role.

The more milk that is removed from the breasts, the more milk will be produced. Milk production relies on the supply and demand principal. Also each breast works alone, if mom breastfeeds more from one breast, that breast will produce more milk than the other, which is why it is possible for a mom to breastfeed from just one breast.

Why does the breast produce less when it is full?

* Prolactin cannot bind to the receptors that trigger the release of more prolactin.

* A whey protein in the milk called (FIL) feedback inhibitor of lactation, inhibits the production of milk when the alveoli is full. Once the alveoli are empty, there will be less FIL and therefore more milk can be produced.

4. Involution: This is when the breasts stop producing milk completely after weaning.


Tracy Behr, CBC, CLD (CBI)

Reference:

Course information on the different stages of lactation.

www.childbirthinternational.com


Other pages on breastfeeding problems in connection with this page on stages of lactation

- How does breast milk production work?

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