What is lactation? Lactation happens when the mammary glands in the breasts of a mother, 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?
Stage 1 ~ Mammogenesis
The first stage of lactation is called Mammogenesis, which occurs 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.
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.
Stage 2 and 3 ~ Lactogenesis
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.
The second stage of lactation is called Lactogenesis: (creation of milk) (stages 1 and 2) This is when a mother 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
Lactogenesis stage 1 and 2 are controlled by hormones.
In stage 1, the mother's breasts may feel swollen; this is because of the alveoli that have started to produce colostrum.
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
stage, the breasts may feel warm and become engorged, if they are not
drained frequently enough. If the mother does not breastfeed, her
breasts will stop producing mature milk and start producing colostrum
again, and then finally stop producing milk altogether. The breasts
will begin to produce colostrum after three days of no milk removal from them.
Stage 3 ~ Galactopoiesis
Lactogenesis stage 3: Also called galactopoiesis. This is the production and maintenance of mature milk from day 9 postpartum until the mother and/or baby decide to wean.
Lactogenesis stage 3 is controlled by the autocrine 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 principle. Also, each breast works alone, if the mother breastfeeds more from one breast, that breast will provide 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 are full. Once the alveoli are empty, there will be less FIL, and therefore more milk can be produced.
Stage 4 ~ Involution
Involution: This is when the breasts stop producing milk entirely after weaning.
Breast Anatomy and Stages of Lactation
Tracy Behr, CBC, CLD (CBI)
Course information on the different stages of lactation.