Breasts and Breastfeeding
Presented by Geoff Shaw
Based on previous lecture by
Prof Roger ShortFaculty of Medicine, Dentistry and Health Sciences,
University of [email protected]
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.