HOW MILK GETS FROM BREAST TO BABY

INTERNAL BREAST ANATOMY

Two divisions of breast tissue:

parenchyma includes the ductular, and lobular-alveolar structures; and

stroma, which includes all the connective, fat, vascular, nerve and lymphatic tissue

Smallest functional unit is the alveolus, made up of secretory epithelial cells, which manufacture milk

INTERNAL ANATOMY

Myoepithelial cells surround the alveolus. These cells can contract the alveolus and squeeze milk from the cells into the lumen of the alveolus.

A capillary network surrounds each alveolus, bringing raw materials for milk synthesis as well as hormones which influence milk production and ejection.

MORE INTERNAL BREAST ANATOMY

Each alveolus empties into a ductule, which connect to other ducts.

10 to 100 alveoli make up a mammary lobule. Branching ducts from each lobule connect to lactiferous ducts.

Each lactiferous duct opens in the nipple through a separate pore. There are approximately 9 major milk ducts. Ducts transport but do not store milk.

ADDITIONAL ANATOMY The mammary fat pad provides support for the

functional tissue. Fat is evenly distributed throughout the breast.

The fourth, fifth and sixth intercostal nerves innervate the breast, including smooth muscles in the nipple and blood vessels.

On the surface of the breast, Montgomery’s tubercles secrete a substance which lubricates and protects the nipple and areola. The secretion helps to prevent nipple infections.

EARLY BREAST DEVELOPMENT

Occurs in three stages: fetal development in utero, during the first two months of life, and in puberty when hormones stimulate the growth of tissue and development of ductular and lobular-alveolar system.

During menstruation, estrogen induces proliferation of the ductal system, and progesterone induces development of the alveoli.

LACTOGENESIS IMATURATION OF BREAST TISSUE

DURING PREGNANCY

In pregnancy, organogenesis is accelerated with intensified growth of ductal and lobular-alveolar systems.

High levels of progesterone cause rapid increase in number of alveoli.

Milk fat and protein synthesis begin in alveoli. Colostrum is produced, although very little is secreted into the ductules and ducts.

LACTOGENESIS IISYNTHESIS OF MATURE

MILK The final stage of breast development

occurs during lactation.

The rapid drop of progesterone caused by delivery of the placenta triggers full secretory role in alveolar cells.

Milk is released into the alveolar lumen and then into the ductules and ducts.

LACTOGENESIS IIIMILK PRODUCTION

Galactopoiesis (Lactogenesis III), the process of milk supply maintenance, occurs in response to milk removal from the breast over the course of the breastfeeding relationship.

Rarely, breast abnormalities may affect milk production.

HORMONES OF LACTATIONPROLACTIN AND OXYTOCIN

Two major hormones control lactation

Prolactin is responsible for milk production. Progesterone is thought to inhibit prolactin. The sudden drop in progesterone after delivery of the placenta triggers an initial increase in prolactin.

Retained placental fragments may be responsible for continuing absence of milk supply.

PROLACTIN

Prolactin is secreted into the blood stream by the anterior pituitary in response to sucking stimulus on the nipple.

Alveolar cells respond to increased serum prolactin by making more milk.

HORMONES OF LACTATION OXYTOCIN

Oxytocin is responsible for releasing milk (the let-down reflex). It causes the myoepithelial cells surrounding the alveoli to contract and push milk out through the ducts.

Oxytocin is released by the posterior pituitary in response to several types of stimulus.

OXYTOCIN II Stimuli include:

Nipple stretching by correct suckling of infant

Massage-like motions of infant’s hands on the breast

Seeing, touching, smelling or hearing her infant, resulting in a conditioned response

Oxytocin response is transient and intermittent.

Women may experience several let-downs during a feeding. Extreme pain or stress may temporarily inhibit oxytocin release.

SUCKING PATTERNS AFFECT HORMONE LEVELS

Inadequate sucking leads to inadequate prolactin stimulation, resulting in inadequate milk supply.

The following may be related to inadequate stimulation:

infrequent or brief feeds;

scheduled feeds (rather than feeding on cue);

no or too few night time feeds;

delayed feeds due to sore nipples;

sleepy infant caused by labor medication or caloric deprivation;

improper latch during feeds;

lack of active or effective sucking.

MILK PRODUCTION

The relative “emptiness” of the breast drives the rate of milk synthesis, i.e., the more frequent the withdrawal of milk, the faster the rate of milk synthesis.

Inadequate sucking will not empty the breast adequately, leading to eventual decrease in milk production.

NEGATIVE EFFECTS OF OVER-FULLNESS OF

BREAST Prolonged over-fullness of the breast

creates internal pressure, which decreases overall milk production. Continuing pressure from milk retention causes engorgement and involution of the lactiferous tissue.

Death of milk-making cells occurs during involution. Alveolar cells will proliferate again during subsequent pregnancies.

IMPACT OF BREAST SURGERY OR INJURY

Breast surgery and injury may affect the patency of the ductal system and/or the innervation of the nipple.

Without patent ducts (as may be the result in some breast surgeries) milk cannot be adequately removed from the breast.

Without proper enervation of the nipple, the stimulus for hormonal release will not be received by the brain.

In the case of injury, milk-making tissue may be transiently or permanently affected.

GOLDSMITH’S SIGN

A significant but rarely occurring finding is when an infant refuses one breast or suddenly rejects one breast, or refuses to nurse on one breast.

This may be an early indication of present or imminent breast cancer. This is referred to as “Goldsmith’s sign.”

THE BABY’S ROLE IN MILK PRODUCTION

Good attachment to the breast

Effective suckling to remove milk

SIGNS OF GOOD ATTACHMENT

Chin touching breast (or nearly so)

Nose touching the breast (or nearly so)

Mouth wide open

Lower lip turned outwards

Areola: more visible above than below the mouth

Breastfeeding Counselling: a training course,

WHO/CHD/93.4, UNICEF/NUT/93.2

SIGNS OF POOR ATTACHMENT

Chin/nose away from breast

Mouth not wide open

Lower lip pointing forward, or turned in

Areola: more visible below than above; or equal amounts Breastfeeding Counselling: a training course,

WHO/CHD/93.4, UNICEF/NUT/93.2

SIGNS OF EFFECTIVE SUCKLING

Slow, deep sucks and swallowing sounds

Cheeks full and not drawn in

Baby feeds calmly

Baby finishes feed by him/herself and seems satisfied

Mother feels no pain

SIGNS THAT A BABY IS NOT SUCKLING EFFECTIVELY:

Rapid, shallow sucks

Cheeks drawn in

Baby fusses at breast or comes on and off

Baby feeds very frequently, for a very long time, but does not release breast and seems unsatisfied or sleeps deeply with no feeding cues for more than 2 hours between feedings

Mother feels pain

BREAST CARE

Clean the breasts with water only.

Washing the breasts once a day as part of general body hygiene is sufficient.

Breasts do not need to be washed before feeds.

Choose a brassiere that fits well and is not too tight.

BREAST CARE CONT.

Mothers who are not breastfeeding need to care for their breasts until their milk dries up.