Note: This document is just for academic purposes and should not be used as a basis for practical treatment, any consequences as a result of practically using this as a guidline will not lead to the publisher held accountable. The breast is a gland consisting primarily of connective and fatty tissues that support and protect the milk producing areas of the breast. The milk is produced in small clusters of cells called the alveoli. The milk then travels down ducts to the nipples. Breast milk provides ideal nutrition and passive immunity for the infant, encourages mild uterine contractions to return the uterus to its pre-pregnancy size and induces a substantial metabolic increase in the mother, consuming the fat reserves stored during pregnancy. Thus this document, will converse in details the process of milk production to its let down and the characteristics of the breast milk.

1. Introduction
The breast is a gland consisting primarily of connective and fatty tissues that support and
protect the milk producing areas of the breast. The milk is produced in small clusters of cells
called the alveoli. The milk then travels down ducts to the nipples. Breast milk provides ideal
nutrition and passive immunity for the infant, encourages mild uterine contractions to return
the uterus to its pre-pregnancy size and induces a substantial metabolic increase in the mother,
consuming the fat reserves stored during pregnancy. Thus this assignment will converse in
details the process of milk production to its let down and the characteristics of the breast milk.

2. Milk production and let down/ Physiology of Lactation
Physiological basis of lactation is divided into 4 phases 1. Preparation of
breasts(Mammogenesis) 2.Synthesis and secretion of breast alveoli(Lactogenesis) 3. Ejection
of Milk(Galactokinesis) 4. Maintenance of lactation(Galactopoiesis)
During pregnancy oestrogen and progesterone secreted by the placenta prepare the breasts for
lactation.The oestrogen inhibits milk production until the end of pregnancy. In the third
trimester of pregnancy colostrum is present and remains for the first 3 days post-partum.
By the third stage of labour (delivery of the placenta), the hormonal production is reduced, and
during the next 48hrs, the blood level of oestrogen and progesterone fall. This stimulates the
anterior pituitary gland to produce the lactogenic hormone (prolactin hormone) which acts on
the acini cells in the breast, and milk is formed.
The milk is pushed along the lactiferous ducts and some is stored in the ampullae which lie just
under the areola.When the infant sucks, he/she takes the nipple and the areola into his mouth,
and partly by a vacuum which is created mostly by a chewing action of his jaws, milk is
pushed into his mouth and he swallows. As the ampulla and lower ducts are emptied, milk is
pushed from the alveoli by contraction of the myoepithelial cells. So, the act of sucking by the
infant is the stimulus that provokes lactation.
This effects a neuro-hormonal reflex mechanism which activates the anterior pituitary lobe to
produce lactotropin, and the posterior pituitary lobe to produce oxytocin which reaches the
breast through the blood stream, leading to contraction of myoepithelial cells, and the
expulsion of milk.
Oxytocin also stimulates uterine contractions causing after pains and lochial discharge during
breastfeeding. With the onset of milk the breasts become larger firmer, heavier, and full of
milk that can be expressed on pressure, or may escape spontaneously. This procedure is
associated with a considerable local throbbing pain extending the axillae.
The let down reflex (Milk ejection.)
This is the discharge of milk from mammary gland. As mentioned above, It depends upon
suckling exerted by the baby and on contractile mechanism in breast, which expels milk from
alveoli into the ducts. Milk ejection is a reflex phenomenon. Infant sickling stimulates the
nerve endings in the nipple and areola, which signals the pituitary gland in the brain to release
two hormones, prolactin and oxytocin.
Prolactin hormones causes the alveoli to take nutrients (proteins, sugars) from the blood supply
and turn them into milk. Then oxytocin causes the cells around the alveoli to contract and eject

3. milk down through the milk ducts. The passing of milk down through the ducts is what is
called the ‘let down (milk ejection) reflex.
The let down is experienced in numerous ways such as; the infant begins to actively suck and
swallow, milk dripping from the opposite breast, a tingling or full sensation (after the first
week of nursing) in the breast or may experience uterine cramping and the woman may feel
thirst.
Characteristics of breast milk.
Breast milk contains about 88.5% of water and 11.5% of solids. Important solids are lactose,
lactalbumin, iron, vitamins A and D and minerals. Breast milk is always considered superior to
animal milk (cow milk or goat milk) because it consists of sufficient quantity of all the
substances necessary for infants like iron, vitamins and minerals. Besides nourishment of
infant, the breast milk also provides several antibodies, which help the infant resist the
infection by lethal bacteria. Even some neutrophils and macrophages are secreted in milk.
These phagocytic cells protect the infant by destroying microbes in the infant’s body.
Characteristics of breast milk are that;
It is suited to the infant’s needs, easily digestible,germ- free, fresh, warm and contains
antibodies, vitamins, calcium, lactose, casein protein, fat, mineral salt and water.
Breast milk also at different stages of lactation is defined by different terms or character such
as;
Colostrum: is a thick, sticky and light yellowish in colour which is produced during the first
few days after delivery. Although secreted in small quantities (30-90ml), it is sufficient to meet
the caloric needs of a normal newborn in the first few days of life.
Transition milk :During a period of 1-2 weeks that follow the colostrum stage the milk
increases in quantity and changes in appearance and composition as per the baby's needs,
protein contents decrease while fat and sugar contents increase. At this time the breasts feel
full, hard and heavy.
Mature milk: This milk is thinner and watery but contains all the nutrients essential for
optimum physical and mental development of the child. Mature milk changes even during the
length of a single feed to exactly suit the needs of a baby.
The mature milk consists of Foremilk and Hind milk: Foremilk is the milk which comes at
the start of a feed and it has a low level of fat and is high in lactose, sugar, protein, vitamins,
mineral and water. It satisfies the baby's thirst and is produced in larger amounts than hind
milk. Hind milk: which comes later in a feed, is richer in fat which makes it look whiter and

4. thicker than foremilk. It satisfies the babies hunger and supplies much of the energy of a
breastfeed. Baby needs both the foremilk and the hind milk for appropriate weight gain. Also,
babies who are fed both foremilk and hind milk sleep well.
Pre-term milk: is a milk produced by a woman who has delivered prematurely. This milk has
more proteins, minerals, immunoglobulin and lactoferrin than the mature milk, making it
suitable for the needs of a pre-term baby. The pre-term milk is ideal food for low birth weight
babies.
Term milk is produced by a woman who has a full term delivery. Its composition is suitable for
normal term baby.

5. Conclusion
This assignment has elucidated the process of milk formation (lactation) and the characteristics
of breast milk. Lactation involves the process of producing milk. For women who are pregnant
or recently gave birth and is normal process which is very essential for the well-being of the
new born`s growth and survival. Hormones signal the mammary glands in a woman`s body to
start producing milk to feed the baby. Breast milk is is the primary source of nutrition for
newborns, containing fat, protein, carbohydrates and variable minerals and vitamins.

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