physiology of lactation new
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Physiology of Lactation
Adapted from the course onBreastfeeding : Advocacy & PracticeMalaysia 2008
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Stages of Lactation(Criteria devised by Peter Hartman )
Mammogenesis
Lactogenesis
Lactogenesis ILactogenesis II
Galactopoiesis
Lactogenesis III
Involution
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Lactogenesis
Lactogenesis I
starts at 28 weeks pregnancy
Substrate for milk productioncollect in breast tissue
Early secretion production ofcolostrum starts
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Lactogenesis II
starts at 3-4 days after delivery- removal of placenta,
progesterone &estrogen =
stimulates milk synthesisBlood flows to breast increases
Transition milk comes in
Copius production of mature milkstarts
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Retained placenta inhibits
Initiationof milk production
depends on changed hormone levels
----- NOT on early suckling
Continuationof milk production
after 3-4 days DOES depend oninfant suckling
Lactogenesis II
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Lactogenesis III or Galactopoiesis
from 10 days after delivery
Mature milk is produced
Production sustained if baby continues
to breastfeed
Volume depends on the amount baby
removes
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Single baby 750 mls / 24 hrs
For Twins - 1500 mls / 24 hrs
Lactogenesis III or Galactopoiesis
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Involution
When other feeds / foods satisfyappetite baby suckle less,production decreases milk
cells die Milk in the breast isreabsorbed.
Last milk produced is more likecolostrum with many protectivebodies
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Role of Hormones(primes mammary glands)
Estrogen growth of ducts
Progesterone growth of alveoli
Placental Lactogen - growth of milk
producing cells in the alveoli
Prolactin helps growth of ducts andalveoli /stimulates alveoli cells to
produce milk
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Prolactin
in blood
Babysuckling
Sensory impulsesfrom nipples
More prolactinsecreted at night
Suppressesovulation
:
Secreted duringand after
feed to produce nextfeed
Prolactin Reflex
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Prolactin Levels
Prolactin blood levels: ng /ml
Menstruating woman: 8 14
End of pregnancy: 200 500
Baseline during lactation:- From delivery to 10 days: 200
- 10 90 days: 60 100- 90 180 days: 50- 180 days 1 year: 30 40
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Oxytocin reflex
Makes uteruscontract
Sensory impulses
from nipplesOxytocin
in blood
Baby
suckling
Works beforeor during
feed to make milk flow
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Worry
Stress
Pain
Doubt
hinderreflexhelpreflex
Thinks lovingly of baby
Sounds / sight of baby
Touching baby
Confidence
Helping and hindering of
oxytocin reflex
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NEUROENDOCRINE PATHWAYSINITIATED BY SUCKLING
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Milk production
First 4 6 weeks after deliveryis very variable
At 5 days = 200 900 ml / 24hours
At 4 6 weeks = 400 1100
ml/24 hours
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Milk production
Milk production starts:
low and increases (up-regulation) inmost women
high and decreases (down-regulation) -
in some womenuntil it adjusts to the needs of the baby.
Milk productionat this
time is not related to
size of baby
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Milk production
By 4 6 weeks, production adjusts to
babys needs
Milk production is now related to size of baby
- regulated by babys demand- babys fat or calorie intake controls appetite
and hence demand
If supplements are given appetite issatisfied demand is less
(Ingram 99, Allen 91,Neville 88)
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Milk Production From Birth
Babys Age mls per day mls per feed
Range Average On Average
Day 1 (0-24 hrs) 7 123 37 7
Day 2 (24-48 hrs) 44 335 84 14
Day 3 (48-72 hrs) 98 775 266 38
Day 4 (72-96 hrs) 385 58
Day 5 (96-120 hrs) 500 70
3 months 750
6 months 800
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Establishing a good milk supply
To establish adequate breastmilk production,the most important factor is:
To remove milk efficiently, a baby must:
To suckle effectively a baby must be:
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Storage of milk in the breast
Milk is made and stored in the breastbetween feeds
- Storage capacity varies , maybe related
to breast size.
Women with small breast can producedplenty of milk.
- If storage capacity low, baby may needto feed more often.
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It is chemical inhibitor
Is an autocrine or local regulator ofbreastmilk synthesis
Is a protein made in the breast itself
If not removed it collects in thealveoli and blocks milk secretion inthe mammary cells
Feedback Inhibitor of Lactation (FIL)
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Factors that impair milk production
1. Inefficient milk removal due to:
- Poor attachment
- Insufficiently suckling- Addition of supplements
- Infrequent feeds
- Short feeds
- No night feeds
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2.Impaired ejection anxiety, pain
(temporary)
3. Retained placenta products(hormones inhibit prolactin)
4. Oestrogens (e.g., in combined
hormonal contraceptives)
5. Pregnancy
Factors that impair milk production
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6. Lack of prolactin
- Sheehans syndrome (afterpostpartum haemorrhage)
- Primary deficiency - (very rare)
- Smoking (nicotine may lead to lowerprolactin levels)
7. Physical abnormality (breast agenesis)
8. Severe malnutrition
Factors that impair milk production
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INVOLUTION
Breastmilk output continues at about thesame level while baby breastfeedsexclusively and on demand
When other foods are given, the babys
appetite are satisfied and he may suckleless.
Breastmilk production decreases, milkcells die
Milk which remains in the breast isreabsorbed.
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Involution
The last milk produced is morelike colostrum, with manyprotective factors, which may
continue to help protect babyagainst some infection.
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