Morphology of the Breast - Harvard Universitysites.fas.harvard.edu/~anth1380/Slides/Lecture...

11

Lecture 17: Lactation Lecture 17: Lactation

•• Labor PainLabor Pain

•• Morphology of the BreastMorphology of the Breast

•• Hormonal Control of Hormonal Control of

LactationLactation

•• Milk CompositionMilk Composition

•• Benefits of LactationBenefits of Lactation

•• Energetics of LactationEnergetics of LactationBehavioral Biology of Women - 2006

Why is Labor Long in Humans?Why is Labor Long in Humans?

Stage 1 Stage 2

•• Dilation and Dilation and

Effacement of cervixEffacement of cervix

•• Mean = 14 hours in Mean = 14 hours in

first birthfirst birth

•• Expulsion of fetusExpulsion of fetus

•• Mean = 50 minutes in Mean = 50 minutes in

first birthsfirst births

•• 20 minutes in later 20 minutes in later

birthsbirths

Why is Labor Long in Humans?Why is Labor Long in Humans?

0 100 200 300 400 500 600 700 800

Baboon

Gorilla

Chimpanzees

Humans

Minutes

First Stage: Dilation and Effacement of Cervix

Second Stage: Expulsion of Fetus

Why is Labor Painful in Humans?Why is Labor Painful in Humans?

The size of fetal head going through pelvis?

Why is Labor Painful in Humans?Why is Labor Painful in Humans?The need for the cervix to dilate to 10 cm to

accommodate the large fetal head?

How is Human Birth Different?How is Human Birth Different?

Although rotation Although rotation

through the pelvis through the pelvis

contributes to the contributes to the

duration and degree of duration and degree of

difficulty during labor difficulty during labor ……

Difficult labor in humans is Difficult labor in humans is

primarily due to the the primarily due to the the

degree of cervical dilation degree of cervical dilation

necessary to accommodate necessary to accommodate

the size of the human fetal the size of the human fetal

head (3x greater than in head (3x greater than in

apes).apes).

22

•• Humans spend significantly more time in Humans spend significantly more time in

the later stages of dilation when pain is the later stages of dilation when pain is

greatest.greatest.

Why is Labor Painful in Humans?Why is Labor Painful in Humans?

•• Apes probably experience relatively little Apes probably experience relatively little

pain during labor because they have pain during labor because they have

relatively little dilationrelatively little dilation

Labor PainLabor Pain

•• Why does relaxation Why does relaxation

help?help?

•• Autonomic nervous Autonomic nervous

systemsystem

>> Parasympathetic Parasympathetic

(relaxation)(relaxation)

>> Sympathetic (fight or Sympathetic (fight or

flight response)flight response)

Assisted Birth in HumansAssisted Birth in Humans

•• Birth is routinely performed with assistance in Birth is routinely performed with assistance in

humans.humans.

•• Emotional support to the motherEmotional support to the mother

•• Mechanical assistanceMechanical assistance

Birth Support (Birth Support (doula doula effect)effect)

Sosa, et al. (1980)Sosa, et al. (1980)

0

10

20

30

40

50

60

70

No

Problems

Intervention

Cesarean

Oxytocin

Length of

Labor

Suported Unsupported

Assisted Birth in HumansAssisted Birth in Humans

•• Birth is routinely performed with Birth is routinely performed with

assistance in humans.assistance in humans.

•• Emotional support to the motherEmotional support to the mother

•• Mechanical assistanceMechanical assistance

>> May be particularly important May be particularly important

for breech births (2 for breech births (2 -- 4% of 4% of

births)births)

(Gregory et al. 1999)

33

Morphology of the BreastMorphology of the Breast

44

Breast DevelopmentBreast Development Breast Changes during PregnancyBreast Changes during Pregnancy

((mammogenesismammogenesis))•• Estrogen causes growth of ducts and Estrogen causes growth of ducts and

proliferation of alveoliproliferation of alveoli

Breast Changes during PregnancyBreast Changes during Pregnancy

•• Estrogen causes growth of ducts and Estrogen causes growth of ducts and

proliferation of alveoliproliferation of alveoli

•• Progesterone causes the alveolar milk Progesterone causes the alveolar milk

glands to matureglands to mature

Breast Changes during PregnancyBreast Changes during Pregnancy

•• ProlactinProlactin,, cortisol cortisol and growth hormone turn and growth hormone turn

breast cells into:breast cells into:

>> Secretory cells that make milkSecretory cells that make milk

>> Muscle cells that will squeeze milk down Muscle cells that will squeeze milk down

through ductsthrough ducts

Morphology of AlveolusMorphology of Alveolus

•• Site of milk synthesisSite of milk synthesis

Morphology of AlveolusMorphology of Alveolus

•• Site of milk synthesisSite of milk synthesis

•• Contained with a capsule of basement membrane which Contained with a capsule of basement membrane which contains contractile contains contractile myoepithelial myoepithelial cells.cells.

55

Stages of Breast Milk ProductionStages of Breast Milk Production

•• MammogenesisMammogenesis: establishment of glandular : establishment of glandular

morphology capable of producing large morphology capable of producing large

quantities of milkquantities of milk

Mammogenesis(complete at 4 mths)

Stages of Breast Milk ProductionStages of Breast Milk Production

•• LactogenesisLactogenesis: establishment of actively : establishment of actively secreting mammary glandsecreting mammary gland

Lactogenesis(Begins at Parturition)

Stages of Breast Milk Production Stages of Breast Milk Production

Hormones of LactationHormones of Lactation

•• GalactopoiesisGalactopoiesis: maintenance of milk secretion: maintenance of milk secretion

Galactopoiesis

Prolactin & Milk ProductionProlactin & Milk ProductionNeuroendocrine Neuroendocrine ReflexReflex

•• Nipple stimulationNipple stimulation

Prolactin & Prolactin &

Milk Milk

ProductionProduction

•• Nipple Nipple

stimulationstimulation

•• Hypothalamus Hypothalamus

stops producing stops producing

prolactinprolactin--

inhibiting factor inhibiting factor

(dopamine)(dopamine)

66

Prolactin & Prolactin &

Milk Milk

ProductionProduction


stops producing stops producing

prolactinprolactin--inhibiting inhibiting

factor (dopamine)factor (dopamine)


secretes VIP secretes VIP

((vasoactive vasoactive

intestinal intestinal

polypeptide)polypeptide)

Prolactin & Milk ProductionProlactin & Milk Production


•• Hypothalamus stops Hypothalamus stops

producing prolactinproducing prolactin--

inhibiting factor inhibiting factor

•• Hypothalamus secretes Hypothalamus secretes

VIP (VIP (vasoactive vasoactive

intestinal polypeptide)intestinal polypeptide)

•• In response,In response, Prolactin Prolactin is is

secreted from secreted from

lactotrophs lactotrophs in the in the

anterior pituitary anterior pituitary

Prolactin & Milk ProductionProlactin & Milk Production


•• Hypothalamus stops Hypothalamus stops

producing prolactinproducing prolactin--inhibiting inhibiting

factorfactor

•• Hypothalamus secretes VIP Hypothalamus secretes VIP

((vasoactive vasoactive intestinal intestinal

polypeptide)polypeptide)

•• In response,In response, ProlactinProlactin is is

secretedsecreted frm lactotrophsfrm lactotrophs in the in the

anterior pituitaryanterior pituitary

•• ProlactinProlactin stimulates mammary stimulates mammary

glands to produce milkglands to produce milk

Suckling and ProlactinSuckling and Prolactin

•• Increased suckling Increased suckling

produces increased milk produces increased milk

production.production.

•• Prolactin Prolactin approaches approaches

level of nonlevel of non--lactating lactating

women in 4women in 4--6 hours6 hours

Prolactin Prolactin in Nonin Non--Lactating Lactating

Women after stimulationWomen after stimulation

0

20

40

60

80

100

120

Baseline Immediate 15 minutes

Breast and Nipple

Breast Alone

Sternum

Forearm

Milk Letdown & OxytocinMilk Letdown & Oxytocin

•• Milk passes from alveoli, via Milk passes from alveoli, via

ducts, to the ducts, to the storage sinusesstorage sinuses

77


•• Milk passes from alveoli, via Milk passes from alveoli, via

ducts, to the ducts, to the storage sinusesstorage sinuses

•• Suckling stimulates mothers Suckling stimulates mothers

autonomic sensory nerves in autonomic sensory nerves in

the breastthe breast

Latching onLatching on

Latching onLatching on

•• Babies latch on to Babies latch on to

the areola,the areola, NOT the NOT the

nipplenipple


•• Suckling stimulates Suckling stimulates

mothers autonomic mothers autonomic

sensory nerves in the sensory nerves in the

breastbreast

•• Sends message to Sends message to

hypothalamushypothalamus


•• Sends message to Sends message to

hypothalamushypothalamus

•• Causes posterior Causes posterior

pituitary to produce pituitary to produce

oxytocinoxytocin


•• Causes posterior pituitary to Causes posterior pituitary to

produce oxytocinproduce oxytocin

•• Stimulates muscle cells in breast Stimulates muscle cells in breast

to contractto contract

88

Milk Composition:Milk Composition: ColostrumColostrum

•• Produced in first few days Produced in first few days after birthafter birth


•• Produced in first few Produced in first few days after birthdays after birth

•• High in protein, low High in protein, low in fat and lactose in fat and lactose (milk sugar)(milk sugar)


•• Rich inRich inimmunoglobulins immunoglobulins (esp.(esp.IgA IgA andand IgGIgG))

•• Establish normal Establish normal bacterial flora of bacterial flora of infantinfant’’s digestive tracks digestive track

•• Provides epidermal Provides epidermal growth factors for final growth factors for final maturation of infant maturation of infant gut.gut.

Breast Milk ImmunityBreast Milk Immunity

•• Immunoglobulins Immunoglobulins in breast milk protects in breast milk protects

newborns against infectious diseasenewborns against infectious disease

99




•• PeyerPeyer’’s s patches in maternal gutpatches in maternal gut




•• PeyerPeyer’’s s patches in maternal gutpatches in maternal gut

•• Lymphocytes lodge in breast and produce Lymphocytes lodge in breast and produce

IgA IgA in breast milk which coats babyin breast milk which coats baby’’s s

intestines and prohibit foreign objects from intestines and prohibit foreign objects from

getting throughgetting through

Milk CompositionMilk Composition

•• ForemilkForemilk——milk milk

stored in ductsstored in ducts

•• Low fat, low protein, Low fat, low protein,

wateredwatered--downdown

•• 1/3 of total milk 1/3 of total milk

volume each nursingvolume each nursing

Milk CompositionMilk Composition

•• HindmilkHindmilk——milk milk stored in alveolar cells stored in alveolar cells

and released during let downand released during let down

•• High fat, high proteinHigh fat, high protein

Benefits of LactationBenefits of Lactation

•• Ingestion by Newborn Humans:Ingestion by Newborn Humans:

•• Lipids in human milk better absorbed than cows milkLipids in human milk better absorbed than cows milk


•• Ingestion by Ingestion by

Newborn Humans:Newborn Humans:

•• Lipids in human milk Lipids in human milk

better absorbed than better absorbed than

cows milkcows milk

•• Amino acids in cowAmino acids in cow’’s s

milk difficult for milk difficult for

newbornnewborn’’s liver to break s liver to break

down into important down into important

proteinsproteins

1010


•• Ingestion by Ingestion by Newborn Humans:Newborn Humans:

•• Lipids in human Lipids in human milk better milk better absorbed than absorbed than cows milkcows milk

•• Amino acids in cowAmino acids in cow’’s s milk difficult for milk difficult for newbornnewborn’’s liver to s liver to break down into break down into important proteinsimportant proteins

•• Form of iron not well Form of iron not well absorbedabsorbed


•• CompositionComposition

•• CowCow’’s milk low in s milk low in nucleotides: 25% nucleotides: 25% human, 6% cowhuman, 6% cow



•• Nucleotides Nucleotides ---- 25% 25% human, 6% cowhuman, 6% cow

•• Processing of cowProcessing of cow’’s milk s milk destroys destroys lactoferrin lactoferrin and and transferrin transferrin and other and other immunological cellsimmunological cells



•• Nucleotides Nucleotides ---- 25% 25%

human, 6% cowhuman, 6% cow

•• Processing of cowProcessing of cow’’s milk s milk

destroys destroys lactoferrin lactoferrin and and

transferrin transferrin and other and other

immunological cellsimmunological cells

•• CowCow’’s milk has different s milk has different

ratios of calcium, ratios of calcium,

phosphorous, magnesium, phosphorous, magnesium,

sodium and zincsodium and zinc


•• Infant Health:Infant Health:

•• Bottle fed babies Bottle fed babies have 2x the illness have 2x the illness rate and rate and

•• 3x hospital 3x hospital admission rate as admission rate as breast fed babiesbreast fed babies


•• Breast fed babies Breast fed babies have lower rates have lower rates of:of:

•• Ear infectionEar infection

•• PneumoniaPneumonia

•• BronchitisBronchitis

•• VomitingVomiting

•• DiarrheaDiarrhea

1111


•• Effects in adultsEffects in adults

•• Lower rates of diabetesLower rates of diabetes

•• Lower rates of asthmaLower rates of asthma

•• Lower cholesterol levelsLower cholesterol levels

•• Lower heart diseaseLower heart disease

•• Lower risk of breast Lower risk of breast

cancercancer

Lactation and Public PolicyLactation and Public Policy

How do we create a more How do we create a more ‘‘breast breast

feedingfeeding”” friendly society?friendly society?

65%

37%27% 28%

0%

20%

40%

60%

80%

1946 1956 1966 1972

Percentage of Women

Breastfeeding in the US

Field Studies of BreastfeedingField Studies of Breastfeeding

1212

Months

Lactation in the !KungLactation in the !Kung

•• Long interbirth intervals Long interbirth intervals

-- 44.1 44.1 mthsmths

•• Patterning of lactationPatterning of lactation

•• 4.06 bouts/hour4.06 bouts/hour

•• 7.83min/hour7.83min/hour

•• 1.92 min/bout1.92 min/bout

•• As child gets older As child gets older ——

increase in length increase in length

betweenbetween boutsbouts


•• Lower estradiol and Lower estradiol and

progesterone in nursing progesterone in nursing

mothersmothers




mothersmothers

•• Correlated with age of Correlated with age of

infant and mean time infant and mean time

between nursing boutsbetween nursing bouts




mothersmothers

•• Correlated with age of Correlated with age of

infant and mean time infant and mean time

between nursing boutsbetween nursing bouts

•• Suggested interSuggested inter--bout bout

interval key variable in interval key variable in

lactation lactation subfecunditysubfecundity

(Konner & Worthman)

1313

Prolactin & Nursing Bout LengthProlactin & Nursing Bout Length

Prolactin

Nursing

Bout

Prolactin, # Nursing Bouts, & TimeProlactin, # Nursing Bouts, & Time

Prolactin threshold for ovulation

Edinburgh Study of BreastfeedingEdinburgh Study of Breastfeeding

Howie and McNeilly

Edinburgh StudyEdinburgh Study

•• Studied 27 breastfeeding Studied 27 breastfeeding and 10 bottle feeding and 10 bottle feeding mothersmothers

•• Lactation/supplementation Lactation/supplementation diariesdiaries

•• Measured urinary Measured urinary hormoneshormones

•• Measure prolactin in bloodMeasure prolactin in blood

Resumption of Ovarian FunctionResumption of Ovarian Function

1414

Supplementation & Ovarian FunctionSupplementation & Ovarian Function Resumption of Ovarian FunctionResumption of Ovarian Function


•• Lactating women resumed ovarian function later Lactating women resumed ovarian function later

postpartum than did bottle feeding womenpostpartum than did bottle feeding women




•• Frequency of ovulation increased with time as Frequency of ovulation increased with time as

lactation was phased outlactation was phased out






•• Rapid resumption of ovarian function in bottle Rapid resumption of ovarian function in bottle

feeders; gradual resumption in breast feedersfeeders; gradual resumption in breast feeders








•• Importance of introduction of supplementary Importance of introduction of supplementary

foodsfoods

1515








•• Importance of introduction of supplementary Importance of introduction of supplementary

foodsfoods

•• Women who conceived while nursing decreased Women who conceived while nursing decreased

the frequency to 3 or fewer times/day.the frequency to 3 or fewer times/day.

Lactation & Supplementation:Lactation & Supplementation:

The GambiaThe Gambia

Supplementation and Breast MilkSupplementation and Breast Milk

•• Gave 130 women supplement increased Gave 130 women supplement increased calories from 1568 to 2291 + vitamincalories from 1568 to 2291 + vitamin

•• No effect on breast milk volume!!No effect on breast milk volume!!

Supplementation and Breast MilkSupplementation and Breast Milk

•• Gave130 women supplement increased Gave130 women supplement increased calories from 1568 to 2291 + vitaminscalories from 1568 to 2291 + vitamins

•• No effect on breast milk volumeNo effect on breast milk volume

•• Protein content slightly increased (6.6%)Protein content slightly increased (6.6%)

•• Milk fat increase (7.9%)Milk fat increase (7.9%)

•• Lactose decrease (Lactose decrease (--7.6%)7.6%)

•• No change in caloriesNo change in calories

•• Vitamin increase from supplementVitamin increase from supplement

Prolactin & SupplementationProlactin & Supplementation

1616

Gambian StudyGambian Study

•• Supplementation had only a small effect on Supplementation had only a small effect on

quantity and quality of breast milkquantity and quality of breast milk

•• Supplementation had a dramatic effect on Supplementation had a dramatic effect on

prolactin levelsprolactin levels

Prolactin Prolactin && Lactational Lactational

AmenorrheaAmenorrhea

•• High levels ofHigh levels of prolactin prolactin associated with associated with

reduced ability for egg to producereduced ability for egg to produce estradiol estradiol

(in culture)(in culture)

•• Evidence now is role may be more indirect.Evidence now is role may be more indirect.

The Toba: Positive Energy Balance The Toba: Positive Energy Balance

and High Nursing Frequencyand High Nursing FrequencyBreast Feeding HypothesesBreast Feeding Hypotheses

•• How to explain variation in duration of How to explain variation in duration of

postpartum period of infecunditypostpartum period of infecundity

•• Nursing Intensity HypothesisNursing Intensity Hypothesis

•• Metabolic Load HypothesisMetabolic Load Hypothesis

Valeggia & Ellison

Nursing Intensity Hypothesis

1717

Nursing intensity hypothesis:Nursing intensity hypothesis:

The more intensive the nursing, the longer the period The more intensive the nursing, the longer the period

of of lactational lactational amenorrheaamenorrhea

Relative metabolic load hypothesis:

The higher the relative cost of nursing, the longer the period of lactational

amenorrhea

1818

Physical activity postpartumPhysical activity postpartum

0

20

40

60

80

Sitting

Standing

Walking

Crouch/Bend

Walk w/load

Laying down

Chop wood

% of observation points .

(Valeggia &

Ellison 2003)

n = 70 women

Focal sampling

10

15

20

25

30

35

1 3 5 7 9 11 13 15 17 19

Month Post-partum

Mean BMI (± SD)

Toba Toba women remain wellwomen remain well--nourished nourished

during the entire postpartum periodduring the entire postpartum period

Valeggia & Ellison (2003)

WHO’s “normal” range

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

-15-14-13-12-11-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3

Months to 1st menses

Mean ∆BMI (± SE)


Changes in energy balance in relation to

time to first postpartum menses

First menses

Average n = 45

Negative

energy balance

Positive energy balance

1919

Mean duration of postpartum amenorrhea Mean duration of postpartum amenorrhea

1010 ((±± 4) months 4) months (n = 122(n = 122))

!Kung-like nursing intensity

US-like nutritional status

Lactational Lactational Amenorrhea in TobaAmenorrhea in Toba

•• Mean = 10.3 monthsMean = 10.3 months

Valeggia & Ellison



•• High nutritional status and high nursing High nutritional status and high nursing

intensity intensity —— leads to short periods of leads to short periods of

lactational lactational amenorrheaamenorrhea

Valeggia & Ellison



•• High nutritional status and high nursing High nutritional status and high nursing

intensity intensity —— leads to short periods of leads to short periods of

lactational lactational amenorrheaamenorrhea

•• Thus, nursingThus, nursing intensity alone is insufficient intensity alone is insufficient

explanationexplanation

Valeggia & Ellison



•• High nutritional status and high nursing High nutritional status and high nursing intensity intensity —— leads to short periods of leads to short periods of lactational lactational amenorrheaamenorrhea

•• Thus, nursingThus, nursing intensity alone is insufficient intensity alone is insufficient explanationexplanation

•• Interaction between nursing intensity and Interaction between nursing intensity and nutritional statusnutritional status

Valeggia & Ellison

Next time ...Next time ...

•• MotherMother--Infant BondingInfant Bonding

•• Fatherhood and changes in Fatherhood and changes in

paternal hormonespaternal hormones

•• CoCo--sleeping and SIDSsleeping and SIDS

•• Parenting styles crossParenting styles cross--

culturallyculturally

2020

Field Studies of BreastfeedingField Studies of BreastfeedingProximate determinants Proximate determinants


Toba Toba women nurse their infants very women nurse their infants very

frequentlyfrequently

0

1

2

3

4

5

6

7

8

1-3 4-6 7-9 10-12 12-15

Age of infant (months)


n = 70

Nursing events durationNursing events duration

0

1

2

3

4

1-3 4-6 7-9 10-12 13-15

Age of the infant (months)

Mean event duration

in min (±SD)


Maternal dietMaternal diet

•• One main meal + snacksOne main meal + snacks

•• Monotonous, calorieMonotonous, calorie--dense dietdense diet

•• Rich in complex carbohydrates and fats Rich in complex carbohydrates and fats

(e.g., fried dough, white bread, noodles, (e.g., fried dough, white bread, noodles,

rice, polenta)rice, polenta)

Determinants of durationDeterminants of duration


•• No association with nursing behavior (frequency, No association with nursing behavior (frequency, duration of individual bouts, total duration of duration of individual bouts, total duration of nursing, all regression p > 0.11)nursing, all regression p > 0.11)

•• No association with No association with staticstatic measures of measures of

maternal maternal energeticsenergetics (e.g., pre(e.g., pre--

pregnancy BMI, average postpartum pregnancy BMI, average postpartum

BMI, BMI at time of 1BMI, BMI at time of 1stst menses, % fat; menses, % fat;

all all pp’’ss > 0.09)> 0.09)

2121

Significant correlation with dynamic, time-dependent measures of maternal energetics (e.g, postpartum energy

balance)

ConclusionConclusion

The pattern of resumption of The pattern of resumption of

postpartum fertility could be postpartum fertility could be

explained by differences in explained by differences in individual individual

metabolic budgetsmetabolic budgets..

Morphology of the Breast - Harvard Universitysites.fas.harvard.edu/~anth1380/Slides/Lecture...

Documents

Transcript of Morphology of the Breast - Harvard Universitysites.fas.harvard.edu/~anth1380/Slides/Lecture...