Lactogenesis: Definition, Breast Anatomy and All Stages Involved in Lactation

It is the production of milk in the mammary glands. This, along with mammogenesis and galactopoiesis, are the different stages of lactation.

Lactation and its stages

What is breastfeeding?

Lactation occurs when the mammary glands in a mother’s breasts produce milk for her baby.

All females have mammary glands to feed their young. The word “mammary” is derived from the Latin word “mammae,” which is similar to the sound that occurs when a baby is searching for the breast.

The anatomy of the breasts

Each breast contains about 20 lobes of glandular tissue (they look like small trees). The “leaves” of these trees are made up of alveoli, which are milk-producing cells.

Milk flows from the alveoli to the ducts and then the ducts and finally exits the nipple through the duct openings. The breast also contains many blood and nerve vessels, and lymphatic vessels.

The different stages of breastfeeding

Stage 1: Mammogenesis

The first breastfeeding stage is called mammogenesis, which occurs when the breasts develop, from birth to puberty, and then the process is completed during pregnancy.

This stage of lactation begins in a woman while she is still in her own mother’s womb, as a tiny embryo. At 12 weeks gestation, the breasts developed nipples, areolas, alveoli (milk-producing cells), and breast buds.


The sex hormones will then develop the breasts until it is born. During puberty, estrogen and pituitary growth factors will cause the breasts to grow. New breast tissue accumulates with each monthly ovulation cycle, up to age 35.

A woman’s breasts are only ready to produce milk once she has become pregnant; This is when the final changes occur in the breasts to allow you to make milk.

The hormones responsible for these changes during pregnancy include prolactin, placental lactogen, estrogen, progesterone, and adrenocorticotropic hormone.

So what changes occur during pregnancy?

  • A network of milk ducts extends and grows within the breast.
  • Montgomery’s areolas and tubercles are enlarged.
  • The nipples become more prominent.

Stage 2 and 3: Lactogenesis

The second stage of lactation is called lactogenesis: (creation of milk) (stages 1 and 2). This is when a mother begins to produce milk. Stage 1 is between mid-pregnancy and two days after delivery (after birth). Stage 2 is between day three and day eight after delivery.

Hormones control stages 1 and 2 of lactogenesis.

In stage 1, the mother’s breasts may feel swollen due to the alveoli that have begun to produce colostrum.

In stage 2:  the alveolar cells close and become closely spaced. This increases the production of lactose, glucose, and lipids in milk and decreases the production of protein, sodium, chlorine, nitrogen, and magnesium.

The breasts can feel warm and plump during this stage if they are not drained often enough. If the mother does not breastfeed, her breasts will stop producing mature milk and begin to produce colostrum again, and eventually, they will stop making milk together.

The breasts will begin to produce colostrum after three days without milk removal.

Etapa 3: Galactopoiesis

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

Stage 3 of stage 3 lactogenesis is controlled by the autocrine system, but hormones still play a role.

The more milk removed from the breasts, the more milk will be produced. Milk production is based on the principle of supply and demand. In addition, each breast works alone; if the mother breastfeeds more than one breast, that breast will produce more milk than the other, so a mother can breastfeed from only one breast.

Why does the breast produce less when it is complete?

  • Prolactin cannot bind to the receptors that trigger the release of more prolactin.
  • A whey protein in milk called a lactation inhibitor (FIL) inhibits milk production when the alveoli are complete. Once the alveoli are empty, there will be less FIL, and therefore more milk can be produced.

Stage 4: Involution

This is when the breasts stop producing milk altogether after weaning.