1. Lactation Flashcards
What is the colostrum?
First milk produced following birth, rich in antibodies
What is the recommendation for breast feeding?
Exclusively for 6 months for optimal lifetime benefits
Benefits of breast feeding to baby?
- Reduced incidence of GI, resp, middle ear infection
- Decreased risk of childhood diabetes, asthma and eczema
- Reduced risk of lactose intolerance
- Improved intellectual and motor development
- Decreased risk of obesity in later life
- Reduced AIDs
- 27% reduced risk of sudden infant death syndrome
What is breast feeding beneficial to the mother?
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
Role of prolactin in lactational amenorrhoea?
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
Breast structure at birth?
The breast consists of lactiferous ducts without any alveoli
Changes to breast at puberty?
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.
Changes to breasts during pregnancy?
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
Breast alveoli development?
- Prior to pregnancy, ducts with few alveoli exist
- In early pregnancy, alveoli grow
- In mid pregnancy, alveoli enlarge and acquire a lumen
- During lactation the alveoli dilate
- After weaning, gland regresses
Pathways of alveoli emptying in breast?
Via lactiferous ducts that are dilated to form lactiferous sinuses which open on the surface of the nipple.
Tissue change in pregnant breast?
Adipose tissue is dominant in non-lactating breast
Glandular tissue only develops fully during pregnancy
Where are the oxytocin receptors in the breast?
At the myo-epithelial cells surrounding alveoli
Where are the prolactin receptors in the breast?
At the milk secreting cells i.e. secretory alveoli
What is “let down”
aka milk ejection reflex
Infant cannot suck milk out of alveoli where is it produced
Controlled by neurohumoral reflex (prolactin **)
2 stages of lactation?
- Milk production
2. Let down
Hormonal changes that initiate lactation?
Steep drop in oestrogen and progesterone after delivery
Hormonal control of lactation?
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
Lactation inhibits…
FSH and LH so interferes with reproductive function
How is lactation inhibited?
- 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.
Two reflexes of lactation?
Suckling reflex
Milk ejection reflex
Role of prolactin in the suckling reflex?
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
What is the role of oxytocin in the milk ejection reflex?
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
How does milk ejection become a conditioned reflex?
Let down in response to the cry of the baby
Oxytocin release is inhibited by catecholamines so stress can inhibit the reflex
Why is correct attachment important?
To avoid engorgement/blocked ducts for mum
Ensure sufficient intake for baby
Difference between colostrum and mature milk production?
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.
Main two changes in milk production?
From week 1-3
- Total calories increase
- IgG and total proteins increase
Values for milk production?
800ml / day
at energy content of 27kJ/L
Composition of mature milk, main:
- Energy source?
- Carbohydrate?
- Protein?
- Fat soluble vitamins?
- Water soluble vitamin?
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
How is immunity promotes by mature milk composition?
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)
