Transcript Anatomy and Physiology of Breastfeeding Linda Klein, RNC, IBCLC Avera McKennan Hospital “From birth through puberty, pregnancy, and lactation, no other human organ displays such dramatic changes in shape,

Anatomy and Physiology
of Breastfeeding
Linda Klein, RNC,
IBCLC
Avera McKennan
Hospital
“From birth through puberty,
pregnancy, and lactation, no
other human organ displays
such dramatic changes in
shape, size, and function, as
does the breast.”
(Riordan, 2004)
4 Phases of Mammary
Gland Development
•
•
Mammogenesis: Begins at puberty
Lactogenesis (Stage I and II):Begins
during pregnancy and ends 3-4 days
after birth
•
Galactopoiesis: Copius milk production
•
Involution
Embryologic Growth
•
•
•
Mammary ridge forms during 5th week
of gestation (Milk Line)
Develops into smooth muscle of nipple
and areola by 12-16 weeks gestation
32-40 weeks becomes mammary tissue
which can secrete colostrum (witch’s
milk)At puberty, estrogen causes breast
growth
BREAST ANATOMY
EXTERNAL ANATOMY
Glandular tissue
DUCTAL SYSTEM
CONNECTIVE TISSUE
NERVE SUPPLY
BLOOD SUPPLY
LYMPH SUPPLY
Changes in Pregnancy
•
Complete mammary development
occurs only during pregnancy
•
Breasts become larger, tender
•
Pigmentation increases in areola
•
Colostrum secreted in second trimester
•
Stretch marks and vascularity increase
HORMONES OF
PREGNANCY
Prolactin
It helps prepare the breasts
for breastfeeding and
promotes the growth of the
baby.
Progesterone
•
•
•
•
Maintains Pregnancy “For gestation”
Aids in development of glandular
tissue, milk-making cells
Inhibits effects of prolactin during
pregnancy
Delivery of placenta ESSENTIAL for
adequate milk supply!
ESTROGEN
Stimulates ductal growth
Mammogenesis
Oxytocin
 It has the effect of making the uterus
contract so that birth happens rapidly.
 It also stimulates the mammary glands
to produce milk.
 Only when progesterone levels drop
close to the birth will the effects of this
hormone be felt.
HOW IS MILK MADE?
Hormonal Control of Milk
Synthesis: Endocrine System
Pregnancy
Delivery of Placenta
Progesterone Levels
are High
Abrupt Withdrawal of
estrogen and progesterone
Milk Secretion is
Inhibited
High Prolactin and
Oxytocin levels
Milk volume “turned
down”
Copious Milk Production
Begins
Lactogenesis
Stage
1 (late pregnancy): Alveolar cells are
differentiated from secretory cells.
Stage
2 (day 2 or 3 to day 8 after birth):
By
day 4-5 days postpartum, estrogen and
progesterone levels have dropped
Milk
secretion begins.
Breasts
are full and warm.
Endocrine
control switches to autocrine
(supply-demand) control
HORMONES OF
LACTATION
PROLACTIN
OXYTOCIN
Neuroendocrine Reflex Arc
Nipple stimulation
causes release of
prolactin and oxytocin
Prolactin is a milk-making
hormone
Oxytocin is a milk-releasing
hormone
Oxytocin and Prolactin
FIL: Feedback Inhibitor of Lactation
Law of Supply and Demand
Whey protein: Increases as breast fills up.
Bathtub analogy
The more FIL rises, the less milk needs to
be made. Tub is full.
To make more milk, empty breasts,
decrease FIL levels. Explains why adequate
pumping is important.
PROLACTIN RECEPTOR
THEORY
Prolactin receptors laid down during breastfeeding in
first two weeks
The more receptors there are, the more milk can be
made
Key analogy
Milk Supply Equation
Sufficient Glandular Tissue +
Intact Nerve Pathways and Ducts +
Adequate Hormones and Hormone
Receptors +
Adequately frequent, effective milk removal
and stimulation =
GOOD MILK PRODUCTION