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Pregnancy n lactation
Dr. Javaria Latif
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Implantation of Blastocyst
Implantation occurs 5thto 7thday after ovulation.
Till implantation uterine milk provides nutrition
Implantation is function of trophoblastic cells
Trophoblastic cells secrete proteolytic enzymes that
digest n liquify adjacent cells on the uterineendometrium
Nutrients n fluid is released , transported by the sametrophoblastic cells to the blastocyst
PLACENTA is formed by
1. Adjacent uterine endometrium2. Adjacent trophoblastic cells
3. Adjacent cells of blastocyst
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Nutrition of embryo
Endometrial stromal cells are swollen (rich in glycogen,lipids n even some minerals)..function of progestronefrom corpus luteum.
When the conceptus implants ,the continued swelling of
these endometrial cells take place , now calledDECIDUAL CELLS.
1stweek after implantation invading the decidua,imbibing n digesting it is the only source of nutrition byembryoit functions till 8thweek after implantation
More than one week after implantation placenta beginsto provide nutrition.
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Development n functionalanatomy of placenta
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Two umbil ical arter ies n on e umbi l ical vein are present in th eumbi l ical cord , a rope like structu re that connects fetus toplacenta.
Five weeks after imp lantat ion ,placenta has become ful lyfun ct ion al, fetal heart has begun to pum p
A layer of epithelia l cel ls of vi l l i n a layer of endothel ial cel ls infetal capil lar ies separate maternal n fetal blood
There is exchange of mater ia l between two s treams of b loodbut no actual mix ing
Oxygen n carbon dioxide are transpo r ted by di f fus ion Glucose use transpo r t prote in on the sur face of troph oblast ic
cel ls
Some substances (e.g. am ino acids) are produ ced by thetroph oblast ic layer of placenta itsel f
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Placental permeability
Initially placental membrane is still thick
with lesser surface area ,its permeability
is low
Later permeability increases as
The surface area increases
Thinning of the membrane takes place
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Diffusion of oxygen through
placenta
By diffusion
Near the end of pregnancy pressuregradient is 20 (5030)
Even this low 0xygen pressure is enoughto transfer oxygen for three reasons
1. Fetal Hb
2. Hb conc. Is 50% greater than that ofmother
3. Double bohr effect
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Double bohr effect
Operating in two directions
In one direction in mother n in other direction in the fetalblood
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Diffusion of carbondioxide
Pressure gradient 2 to 3 mmHg
Very soluble
DIFFUSION OF FOOD STUFF
1. Glucosefacillitated diffusion
2. Fatty acidsslower transport
3. Potassium
4. Sodium
5. chlorides
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Excretion of waste products
1. Urea
2. Uric acid
3. creatinine
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HORMONES OFPREGNANCY
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HUMAN CHORIONIC
GONADOTROPHIN Secreted by the syncytial
trophoblastic cells coincidentalwith the development oftrophoblastic cells from earlyfertilized ovum, in the fluids ofmother
8 to 9 days after ovulation(shortly after blastocystimplants) HCG can bemeasured in blood
Its level reaches maximum 10
to 12 weeks Decreses back to lower value
16 to 20 weeks
1. Causes persistence of corpusluteum for next 4 months
2. Continued secretion ofestrogen n progesteronecauses decidual formation nmaintenance
3. Prevents menstruation4. Corpus luteum involutes in the
fourth month of gestation
5. Removal of corpus luteumbefore 7 to 12 weeks ofpregnancy leads to abortion
6. In testes of male fetus it actsas interstitial cell stimulatingfactor resulting in testosteroneproduction
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Estrogen byplacenta
Produced by syncytial
trophoblastic cellsNot secreted de novo
instead secreted fromandrogenic steroid
compounddehydroepiandrosteroneand hydroxydehydroepiandrosterone
Estradiol, estrone,estriole
are formedCortices of fetal adrenal
glands are large
Enlargement of
female uterus
female breast
External genital organ Relaxes pelvic ligament
Symphysis pubisbecomes elastic
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Progesterone
by p lacenta
1. Development of
decidual cells
2. Decreases contractility
of pregnant uterus
3. Even before
implantation it provides
nutrition to developing
conceptus by increasingthe secretion of fallopian
tube n uterus
4. Breast preparation for
lactation
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Human cho r ion ic
somatomammot r
op in(human p lacental
lactogen)
1. Secreted during fifth week ofpregnancy
2. In larger quantities than any
other hormone of pregnancyalthough the function isunclear
3. partial development ofmothers breast n lactation
4. Week effect like growthhormone
5. Decreases insulin sensitivityand glucose usage bymother
6. Mobilization of fat stores ofmother providing alternatesource of energy utilization
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Other hormones in pregnancy
Pitui tary gland Cortoco steroid Thyroid
Corticotropin
thyrotropinProlactin
FSH, LH
Glucocorticoids
Aldosterone(pregnancy
induced HT)
50% increase in
size n thyroxineHCGHUMAN CHORIONIC
THYROTROPIN
Prathyroid
glands
Relaxin by
ovaries/placen
ta
pregnancy n
lactation
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Pre-eclampsia n eclampsia
Rapid rise in B.P during lastmonths of pregnancy
Protein urea
Excessive salt n waterretention
Wt. gain Edema
Arterial spasm
Renal blood flow n GFRdecreases
Proteins deposit in glomerular
basement membranes
Initiated by insufficent bloodsupply to placenta
Placental Release ofsubstances that cause widespread endothelial dysfunction
Eclampia has extreme degreeof these changes
Vascular spasm through outthe body
Clonic siezures/coma
Anithypertensives
Termination of pregnancy
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parturition
Bir th of baby
Strong rhythm ical contract ion of
uterus, unt i l baby is expel led
Hormonal n mechanical changes
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Hormonal factors
Estrogen to
progesterone rat io
increases sufficiently
towards the end ofpregnancy
Oxytoc in
receptors in uterus
oxytocin release
Stretching of cervix causeneurogenic reflex through
hypothalamus
Fetal hormones
Oxytocin
Prostaglandin
cortisol
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Mechanical factors
Stretch of uterine musculature
Stretch of cervix
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Onset of labour Braxton Hick contract ions
Labour contract ions Posi t ive feed back theory by streching of c erv ix
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Abdom inal musc le cont rac t ion
Mechanics of partur i t ion
Separat ion n del ivery o f p lacenta Labou r pains
Invo lut ion of the u terus after
partur i t ion
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LACTATION
DEVELOPMENT OF BREAST
Growth of ductal system
Estrogen, Growth hormoneprolactin,cortisol,insulin
Development of lobule alveolar system
progesterone
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Initiation of lactation
Prolactin
Estrogen n progesterone
Human chorionic somatotropin Growth hormone
Cortisol
Insulin Parathyroid
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Hypothalmic control of prolactin secretion
Supression of monthly ovarian cycles in
nursing mothers for many months after
delivery
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Eject ion process in the mi lk
secretionfunction of oxytocin
Inh ib i t ion of m i lk eject ion
Milk composi t ion n metabo l ic d rain
on mother caused by lactat ion
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Antibodies n other macrophages in the
human milk
Special protection against ESCHERICIA
COLI
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