Pregnancy n Lactation

8/12/2019 Pregnancy n Lactation

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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

Pregnancy n Lactation

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