Physiology of Lactation New

7/31/2019 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



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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



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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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Physiology of Lactation New

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