1. Lactation

Question 1

What is the colostrum?

Answer 1

First milk produced following birth, rich in antibodies

Question 2

What is the recommendation for breast feeding?

Answer 2

Exclusively for 6 months for optimal lifetime benefits

Question 3

Benefits of breast feeding to baby?

Answer 3

1. Reduced incidence of GI, resp, middle ear infection
2. Decreased risk of childhood diabetes, asthma and eczema
3. Reduced risk of lactose intolerance
4. Improved intellectual and motor development
5. Decreased risk of obesity in later life
6. Reduced AIDs
7. 27% reduced risk of sudden infant death syndrome

Question 4

What is breast feeding beneficial to the mother?

Answer 4

Promotes recovery from childbirth
Promotes return to "normal" body weight
Promotes a period of infertility
Reduce risk of pre-menopausal breast cancer
Possibly reduces risk of ovarian cancer
Possibly improves bone mineralisation

Question 5

Role of prolactin in lactational amenorrhoea?

Answer 5

Prolactin suppresses hypothalamic release of GnRH and therefore pituitary FSH and LH.
–> Prevents follicular growth, ovulation and menstruation
Women who EXCLUSIVELY breast feed their baby will delay the onset on MCs

Question 6

Breast structure at birth?

Answer 6

The breast consists of lactiferous ducts without any alveoli

Question 7

Changes to breast at puberty?

Answer 7

Under influence of oestrogen the ducts proliferate and masses of alveoli form at the ends of the branches
Each cycle involves proliferative changes in the alveoli and there may be secretory activity.

Question 8

Changes to breasts during pregnancy?

Answer 8

Under influence of oestrogen, progesterone and prolactin the glandular portion of the breast undergoes hypertrophy (replacing the adipose tissue)
From week 16, the breast tissue is fully developed for lactation but is quiescent awaiting activation
After parturition the breast produces colostrum before mature milk production begins

Question 9

Breast alveoli development?

Answer 9

1. Prior to pregnancy, ducts with few alveoli exist
2. In early pregnancy, alveoli grow
3. In mid pregnancy, alveoli enlarge and acquire a lumen
4. During lactation the alveoli dilate
5. After weaning, gland regresses

Question 10

Pathways of alveoli emptying in breast?

Answer 10

Via lactiferous ducts that are dilated to form lactiferous sinuses which open on the surface of the nipple.

Question 11

Tissue change in pregnant breast?

Answer 11

Adipose tissue is dominant in non-lactating breast

Glandular tissue only develops fully during pregnancy

Question 12

Where are the oxytocin receptors in the breast?

Answer 12

At the myo-epithelial cells surrounding alveoli

Question 13

Where are the prolactin receptors in the breast?

Answer 13

At the milk secreting cells i.e. secretory alveoli

Question 14

What is “let down”

Answer 14

aka milk ejection reflex
Infant cannot suck milk out of alveoli where is it produced

Controlled by neurohumoral reflex (prolactin **)

Question 15

2 stages of lactation?

Answer 15

1. Milk production

2. Let down

Question 16

Hormonal changes that initiate lactation?

Answer 16

Steep drop in oestrogen and progesterone after delivery

Question 17

Hormonal control of lactation?

Answer 17

Drop in oestrogen and progesterone after delivery

Prolactin surges each time mother nurses baby due to nerve impulses from nipples to hypothalamus.
-So no stimulation means no milk production
When not nursing, hypothalamus prolactin inhibitory hormone

Question 18

Lactation inhibits…

Answer 18

FSH and LH so interferes with reproductive function

Question 19

How is lactation inhibited?

Answer 19

• Prolactin controls/promotes milk production.
• Prolactin is secreted during pregnancy (from anterior pituitary), but its action is inhibited by high levels of progesterone and oestrogens and hPL (human placental lactogen).
• These steroid levels fall after parturition and milk production begins.

Question 20

Two reflexes of lactation?

Answer 20

Suckling reflex

Milk ejection reflex

Question 21

Role of prolactin in the suckling reflex?

Answer 21

Suckling stimulus inhibits the hypothalamic release of dopamine (PIF) and prolactin is released in proportion to the strength and duration of the suckling
The baby orders up its next meal as it suckles

Question 22

What is the role of oxytocin in the milk ejection reflex?

Answer 22

Suckling stimulates neurones in the hypothalamus to synthesise oxytocin which is carried to posterior pituitary
The release of oxytocin into the blood stream acts on myo-epithelial cells in the alveoli = “let down” of milk

Question 23

How does milk ejection become a conditioned reflex?

Answer 23

Let down in response to the cry of the baby

Oxytocin release is inhibited by catecholamines so stress can inhibit the reflex

Question 24

Why is correct attachment important?

Answer 24

To avoid engorgement/blocked ducts for mum

Ensure sufficient intake for baby

Question 25

Difference between colostrum and mature milk production?

Answer 25

Colostrum (produced for about a week)
Mature milk after 21 days pp

Colostrum:

• Fewer calories
• Fewer carbohydrates
• Less fat
• More protein
• Fewer water-soluble vitamins
• More fat-soluble vitamins (esp vit A)
• More zinc and sodium
• More IgG, IgA.

Question 26

Main two changes in milk production?

Answer 26

From week 1-3

1. Total calories increase
2. IgG and total proteins increase

Question 27

Values for milk production?

Answer 27

800ml / day

at energy content of 27kJ/L

Question 28

Composition of mature milk, main:

• Energy source?
• Carbohydrate?
• Protein?
• Fat soluble vitamins?
• Water soluble vitamin?

Answer 28

Main energy source is fat - easily digested emulsified globules (4.2 gm/100mls polyunsaturated fat)

Lactose main carbohydrate (7g/100ml)
• promotes the growth of Lactobacillus bifidus
• provides galactose for myelin formation

Proteins: casein and lactalbumin (1.1g/100ml)

Fat soluble Vitamins: A,D,E,K

Water soluble vitamins: B6, B12, C, Folate, Niacin, Riboflavin, Thiamine

Question 29

How is immunity promotes by mature milk composition?

Answer 29

Gut is initially sterile and first feeds will contain acute dose of antigens and bacteria (600 sp of bacteria identified in breast milk including beneficial Bifidobacterium sps)