Breasts and Breastfeeding

Presented by Geoff Shaw

Based on previous lecture by

Prof Roger ShortFaculty of Medicine, Dentistry and Health Sciences,

University of Melbourner.short@unimelb.edu.au

UNIB30001 Reproductive Physiology

Photos: G Shaw. Original print in AIPP exhibition, Adelaide Convention Centre

Photo: G ShawSA art gallery

Photos: G Shaw

Breastfeeding is a natural part of development for mammals. Why does cause embarrassment or shame?

Major problem of mothers starting breastfeeding is sore nipples. Need to get whole areola into mouth so nipple is at back of throat. Proper positioning critical.

New Guinea Highlanders. Girls aged 2, 4, 6, … 16, 18, 20Only 20 year old is likely to be fertileNote lack of embarrassment – exposed breasts are natural.

Marshall & Tanner, 1972

Tanner stages of breast development pubertal changes

Sir Astley Cooper injected duct openings with different coloured dyes (in mortuary specimens) to show each duct connects to a lobe of the gland.

Gorilla in London Zoo, caught as infant in central africa. No male. Never pregnant. Note lack of breast development. Only got breast development later after pregnancy.

THE MALE’S VIEW OF THE FEMALE

orang utan

gorilla

chimpanzee

woman Sexual signals in primates

Humans only spp where breasts develop without pregnancy.

Note chimpanzee – sexual skin of vulva swells and colours dramatically during oestrus signalling fertility.

Compare with human – breasts always large regardless of stage of cycle (though there are changes in breast sensitivity and small changes in size)

!Kung mother and 3 year old child, Kalahari desert

Traditional life style – long lactation of 3-4 years is the norm.

Note how the baby has the whole areola in its mouth – correct positioning.

SUCKLING DURATION

Frequency Durationper hour (min)

!Kung Hunter-gatherers 4 2

Chimpanzees 4 2

Gorillas 1 2.5

Compare !Kung – short feeds many times a day to recommendations of paediatric texts – eg feed for 20 mins every 3 hours. Not the natural pattern. Is this abnormal pattern driven by worries about showing breasts/breastfeeding in public?

BIRTH INTERVALS

!Kung Hunter-gatherers 4.1 years

Chimpanzees 5.7 years

Gorillas 3.8 years

Orang Utans 5-7 years

Suckling frequency, via neuroendocrine feedback, controls birth spacing.

Breastfeeding is nature’s contraceptive.If you erode breastfeeding you erode the contraceptive effect. The bottle of baby formula is a “conceptive”.

Milk ejection reflex

Sucking neural signal Oxytocin releaseNote drop of milk on the left teat – both breasts responding to the OT.

Neural signal OT = today’s feedNeural signal Prl = tomorrow’s feed

Right breast

Left breast

delivery1.0

0.8

0.6

0.4

delivery

Sen

siti

vity

1.0

0.8

0.6

0.4

36 38 1 2 3 4DaysWeeks

2-point discrimination test

Breast sensitivity increases dramatically after birth.

Increased sensitivity increased neural feedback OT/Prl

H

P

LACTATIONAL AMENORRHOEA

Nipple stimulation by sucking infant sends afferent neural stimuli to hypothalamus

Nipple sensitivity to tactile stimuli is markedly enhanced after delivery

Ovary

Non lactating, no contraception

Lactating, no contraception

Post partum, lactating + post menstrual contraception

Contraceptive effects of breastfeeding

Short RV, Lewis PR, Renfree MB, Shaw G (1991) The contraceptive effects of extended periods of lactational amenorrhoea. The Lancet 337, 715-717.

Mo

nth

ly %

ris

k o

f pre

gna

ncy

Months postpartum Months of lactational amenorrhoea

Cu

mu

lativ

e %

P

roba

bili

ty o

f pre

gn

ancy

% w

omen

am

eno

rrh

eic

-▽-

Study of well nourished Australian women

The effect of breastfeeding on fertility in the absence of contraceptives

!Kung hunter gatherersMean Live births = 4.7

N. American HutteritesMean Live births = 10.6

Mrs McNaughtLive births = 22

Full Breast Feeding

Breast FeedingEarly Weaning

NoBreast Feeding

Years since first conception0 4 8 12 16 20 24 28

Mean Birth Interval 4.1 yrs

Mean Birth Interval 2.0 yrs

Mean Birth Interval 1.3 yrs

Thapa, S., Short, RV and Potts M (1988) Breast feeding, birth spacing and child survival. Nature 335, 679-682

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

WH

O 8

9977

observed total fertilityobserved fertility inhibited by breastfeeding, andby contraception

Total fecundity per woman

AFRICA

AMERICAS

ASIA

Data for indigenous communities in different continents. In Africa breastfeeding is the best contraceptive by far – readily available, cost free.

Lord and Lady Remingham and their children. 17th century

The gentry tended to not breastfeed (at best a wet-nurse) so ended up with huge families and often high infant mortality rates

Mornington Island, Queensland: 20th century. Mother’s age 21

Government policy to suppress breastfeeding (primitive!) and promote bottle feeding, under the guise of doing something about aboriginal health. Resulted in vast increase in fertility rates, increased infant mortality …

Twins and their mother. Pakistan 1968

Boys more valued than girls so boy got breast, girl formula.

Maine, O and McNamara, R (1985) Birth spacing and child survival. Centre for Population and Family Health, Columbia University

Longer birth intervals are associated with a halving of infant mortality

Death rates among infants born at the end of a short or a long birth interval

0 50 100 150 200 250

GhanaKenya

LesothoSenegal

SudanColombia

Costa RicaEcuador

HaitiJamaica

MexicoPanama

PeruBangladesh

IndonesiaJordanKorea

MalaysiaNepal

PakistanPhilippines

Sri LankaSyria

Thailand

Afr

ica

Latin

Am

eric

aA

sia

Reg

ion

Annual Death Rate per 1000 children aged 1-4

Long Interval (2-4 years) Short Interval (<2 years)

Kwashiorkor, Zambia

Kwashiorkor: Protein malnutrition particularly common in developing countries in the transition from breastfeeding.

KWASHIORKOR

“The evil eye of the child in the womb

upon the child already born”

A disease of short birth intervals?

1. ingest pathogen

2. Activate B_cells in Peyer’s Patches

3. migrate to breast, become plasma cells

4. secrete IgA into milk

THE ENTERO-MAMMARY CIRCULATION

modified from:http://www.unsystem.org/scn/archives/npp11/ch08.htm

Melamine in powdered milk affects 50,000 Chinese babies

https://en.wikipedia.org/wiki/2008_Chinese_milk_scandal

Melamine is cheap and is nitrogen rich so added to baby formula to increase the assayed protein content.

But melamine is toxic.

Does infant formula cause obesity?

… Breastfeeding, on the other hand, has a protective effect on child overweight and obesity by inducing lower plasma insulin levels, thereby decreasing fat storage and preventing excessive early adipocyte development. Plausible biological mechanisms underlying the protective effect of breastfeeding against obesity are based on the unique composition of human milk and the metabolic and physiological responses to human milk.

Oddy (2012) Breastfeeding Reviews 20:7-12http://www.ncbi.nlm.nih.gov/pubmed/22946146

Breastfeeding halves a woman’s risk of breast cancer.

The longer she breastfeeds her infants, the greater the protection.

Stuebe (2009) The Risks of Not Breastfeeding for Mothers and Infants. Rev Obst Gynecol vol 2.

• For infants, not being breastfed is associated with an increased incidence of infectious morbidity, as well as elevated risks of childhood obesity, type 1 and type 2 diabetes, leukemia, and sudden infant death syndrome.

• For mothers, failure to breastfeed is associated with an

increased incidence of premenopausal breast cancer, ovarian cancer, retained gestational weight gain, type 2 diabetes, myocardial infarction, and the metabolic syndrome.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2812877/

Photo by RV Short

http://www.nature.com/articles/srep12933

Gene expression in breastmilk cells is associated withmaternal and infant characteristics

Twigger AJ et al (2015)

Results

• Breastmilk cell gene expression varies amongst women

• Breastmilk gene expression correlates with genes of similar function

• Breastmilk cell gene expression is associated with mother/infant demographic characteristics

Sci Rep. 2015 Aug 10;5:12933. doi: 10.1038/srep12933.

Twigger AJ1, Hepworth AR1, Tat Lai C1, Chetwynd E2, Stuebe AM2, Blancafort P3, Hartmann PE1, Geddes DT1, Kakulas F1.

http://www.nature.com/articles/srep12933

Gene expression in breastmilk cells is associated withmaternal and infant characteristics

Twigger AJ et al (2015)

Conclusions

This study highlights the heterogeneity of breastmilk cell content and associations with characteristics of the breastfeeding mother-infant dyad. Interestingly, the lack of certain correlations, such as between breastmilk cell gene expression and maternal age, parity or mode of delivery, suggests that these characteristics may not important factors influencing total breastmilk cell gene expression in our cohorts. We identified core genes such as CK5, CK14, ESRRB and α-LA that are prevalent in breastmilk cells across mothers. Many of them show important interactions and may be involved in mammary gland function, lactation performance, and/or infant development in light of the recently reported integration of breastmilk cells into the infant. Interestingly, some of the interactions found here between dyad demographic characteristics and genes such as α-LA and GDF3 may potentially explain abnormalities associated with low breastmilk supply and preterm birth, and warrant further investigation. In the future, breastmilk cellular analyses both at the protein and mRNA levels, considered together with dyad demographic characteristics, may be a useful routine practice in hospitals particularly in neonatal intensive care units, in the management of low milk supply, and during treatment of maternal and/or infant infections.