PREGNANCY AND PREGNANCY AND LACTATIONLACTATION

Importance of physiology of pregnancyImportance of physiology of pregnancy It is concerned withIt is concerned with

- the nutrition to the growing fetus- the nutrition to the growing fetus

- the maternal changes needed to provide a- the maternal changes needed to provide a

adequate nutrition to the growing fetusadequate nutrition to the growing fetus

- the maternal changes required for child - the maternal changes required for child

birth and lactationbirth and lactation

MATURATION AND MATURATION AND FERTILIZATION OF OVUMFERTILIZATION OF OVUM

In ovary ovum is in In ovary ovum is in primary oocyteprimary oocyte stage stage

Shortly before release it releases 1Shortly before release it releases 1stst polar polar body and becomes body and becomes secondary oocytesecondary oocyte

At this stage ovum is ovulated into At this stage ovum is ovulated into abdominal cavity and it enters the abdominal cavity and it enters the fimbriated end of one of fallopian tubefimbriated end of one of fallopian tube

Entry of ovum into fallopian tubeEntry of ovum into fallopian tube

--After ovulation the ovum along with attached After ovulation the ovum along with attached granulosa cells k.a. granulosa cells k.a. corona radiatacorona radiata is expelled is expelled into peritoneal cavity to enter fallopian tubesinto peritoneal cavity to enter fallopian tubes

-The fimbriated ends of fallopian tubes are -The fimbriated ends of fallopian tubes are lined by ciliated epithelium and these cilia are lined by ciliated epithelium and these cilia are activated by estrogen from ovariesactivated by estrogen from ovaries

-The cilia beat towards the ostium of fallopian -The cilia beat towards the ostium of fallopian tubes helping ovum to enter ampulla of tubes helping ovum to enter ampulla of fallopian tubesfallopian tubes

-The ovum is then held up at ampullary – -The ovum is then held up at ampullary – isthmic junction for 2 to 3 daysisthmic junction for 2 to 3 days

During this time :During this time :

-if no fertilization occurs the ovum degenerates -if no fertilization occurs the ovum degenerates and diesand dies

-if fertilization takes place , cell division occurs -if fertilization takes place , cell division occurs until blastocyst is transported into uterus this until blastocyst is transported into uterus this is achieved by relaxation of sympathetically is achieved by relaxation of sympathetically innervated muscle of the isthmus assisted by innervated muscle of the isthmus assisted by ciliary action towards uterusciliary action towards uterus

Transport of spermatozoa from the vagina to ampullaTransport of spermatozoa from the vagina to ampulla

-After intercourse millions of sperms are deposited in vagina but -After intercourse millions of sperms are deposited in vagina but only a few sperms are transported within 5 to 10 min upwards only a few sperms are transported within 5 to 10 min upwards from vagina through uterus to ampullae of fallopian tubesfrom vagina through uterus to ampullae of fallopian tubes

-This transport is assisted by contractions of uterus and fallopian -This transport is assisted by contractions of uterus and fallopian tubes caused by prostaglandins in seminal fluid and oxytocin tubes caused by prostaglandins in seminal fluid and oxytocin released by post pituitary gland of femalereleased by post pituitary gland of female

-Fertilization occurs in ampulla of either of fallopian tubes-Fertilization occurs in ampulla of either of fallopian tubes -The sperm has to pierce corona radiata and zona pellucida with -The sperm has to pierce corona radiata and zona pellucida with

acrosomal reactionacrosomal reaction to reach ovum to reach ovum -Once the sperm has entered ovum the oocyte divides again to -Once the sperm has entered ovum the oocyte divides again to

form mature ovum, the female pronucleus and the sperm forms form mature ovum, the female pronucleus and the sperm forms the male pronucleus each having 23 unpaired chromosomesthe male pronucleus each having 23 unpaired chromosomes

-These then unite to form fertilized ovum-These then unite to form fertilized ovum

-sperm binds to a sperm receptor called ZP3 in the -sperm binds to a sperm receptor called ZP3 in the zona and this is followed by zona and this is followed by Acrosomal reactionAcrosomal reaction

--Acrosomal reaction involves the breakdown of Acrosomal reaction involves the breakdown of acrosome, release of enzymes likeacrosome, release of enzymes like Acrocin Acrocin which which facilitates penetration of sperm into zona pellucidafacilitates penetration of sperm into zona pellucida

-one sperm reaches the ovum membrane, fusion to -one sperm reaches the ovum membrane, fusion to membrane is mediated by membrane is mediated by FertilinFertilin a protein present on a protein present on surface of sperm headsurface of sperm head

-the fusion provides a signal that initiates development-the fusion provides a signal that initiates development

-the fusion also sets off a reduction in membrane -the fusion also sets off a reduction in membrane potential of ovum that prevents polyspermy i.e. potential of ovum that prevents polyspermy i.e. fertilization of ovum by more than one spermfertilization of ovum by more than one sperm

Transport of fertilized ovum in the fallopian tubeTransport of fertilized ovum in the fallopian tube- After fertilization 3 to 5 days are required to After fertilization 3 to 5 days are required to

transport fertilized ovum into uterine cavitytransport fertilized ovum into uterine cavity- This is aided by epithelial secretion, action of ciliated This is aided by epithelial secretion, action of ciliated

epithelium that lines the tube and weak contractions epithelium that lines the tube and weak contractions of fallopian tube.of fallopian tube.

- Increased progesterone secretion causes tubular Increased progesterone secretion causes tubular relaxing effect that also allows entry of fertilized relaxing effect that also allows entry of fertilized ovum into the uterusovum into the uterus

- This delayed transport of fertilized ovum through the This delayed transport of fertilized ovum through the fallopian tube allows several cell divisions to occur fallopian tube allows several cell divisions to occur and the ovum is now called a and the ovum is now called a blastocyst blastocyst consisting of consisting of 100 cells100 cells

- During this stage large secretions formed by fallopian During this stage large secretions formed by fallopian tubes secretory cells nourish developing blastocysttubes secretory cells nourish developing blastocyst

Implantation of Blastocyst in the UterusImplantation of Blastocyst in the Uterus- After reaching uterus, Blastocyst remains in uterine After reaching uterus, Blastocyst remains in uterine

cavity for 1-3 days before implantationcavity for 1-3 days before implantation- During this time it is nourished by uterine secretion During this time it is nourished by uterine secretion

called called uterine milkuterine milk- Implantation results from action of trophoblast cells, Implantation results from action of trophoblast cells,

that develop over surface of blastocyst, the outer layer that develop over surface of blastocyst, the outer layer called ascalled as syncytiotrophoblastsyncytiotrophoblast and inner called as and inner called as cytotrophoblastcytotrophoblast

- These cells secrete proteolytic enzymes that digest and These cells secrete proteolytic enzymes that digest and liquefy adjacent uterine endometriumliquefy adjacent uterine endometrium

- Once implantation takes place, the trophoblast cells and Once implantation takes place, the trophoblast cells and adjacent cells from uterine endometrium proliferate adjacent cells from uterine endometrium proliferate rapidly to form the placentarapidly to form the placenta

Early nutrition of embryoEarly nutrition of embryo ProgesteroneProgesterone: secreted by corpus luteum converts the : secreted by corpus luteum converts the

endometrial stromal cells into large swollen cells endometrial stromal cells into large swollen cells containing extra quantities of glycogen, proteins, lipids containing extra quantities of glycogen, proteins, lipids and mineralsand minerals

Later when conceptus implants in the endometrium the Later when conceptus implants in the endometrium the continued secretion of progesterone causes the continued secretion of progesterone causes the endometrial cells to swell more and store more endometrial cells to swell more and store more nutrients. These cells are called nutrients. These cells are called decidual cellsdecidual cells

The trophoblast cells invade the decidua, digesting and The trophoblast cells invade the decidua, digesting and imbibing it, the stored nutrients in the decidua are used imbibing it, the stored nutrients in the decidua are used by embryo for growth and development upto 8 wksby embryo for growth and development upto 8 wks

PlacentaPlacenta also begins to provide nutrition after 16 also begins to provide nutrition after 16thth day day beyond fertilizationbeyond fertilization

PlacentaPlacenta The trophoblastic cords from the blatocyst are The trophoblastic cords from the blatocyst are

attaching to uterus, blood capillaries from attaching to uterus, blood capillaries from embryo also grow into chords.embryo also grow into chords.

By 16By 16thth day blood starts to be pumped by heart day blood starts to be pumped by heart of embryoof embryo

At the same time blood sinuses with maternal At the same time blood sinuses with maternal blood starts to develop around trophoblastic blood starts to develop around trophoblastic cordscords

The trophoblastic cells send out more The trophoblastic cells send out more projections which become placental villi into projections which become placental villi into which fetal capillaries growwhich fetal capillaries grow

The placenta combines the function of The placenta combines the function of alimentary tract, kidneys and lungs for fetusalimentary tract, kidneys and lungs for fetus

In placenta the fetus blood flows through In placenta the fetus blood flows through two two umbilical arteriesumbilical arteries into capillaries of villi then into capillaries of villi then back through back through single umbilical veinsingle umbilical vein into fetus into fetus

The mothers blood flows from her uterine The mothers blood flows from her uterine arteries into maternal sinuses that surround arteries into maternal sinuses that surround villi and then back into uterine veinsvilli and then back into uterine veins

The total surface area of villi of mature The total surface area of villi of mature placenta is only a few square meters but placenta is only a few square meters but exchange of nutrients via diffusion is enormousexchange of nutrients via diffusion is enormous

Functions of placentaFunctions of placenta 1.Diffusiom of oxygen through placental membrane1.Diffusiom of oxygen through placental membrane

-Oxygen passes through simple diffusion-Oxygen passes through simple diffusion - Mean Po2 in maternal blood is 50mmHg and mean - Mean Po2 in maternal blood is 50mmHg and mean

Po2 in fetal blood is 30mmHg so mean pressure Po2 in fetal blood is 30mmHg so mean pressure gradient for diffusion for oxygen is 20mmHggradient for diffusion for oxygen is 20mmHg

-Reasons why fetus gets sufficient O2 inspite of low -Reasons why fetus gets sufficient O2 inspite of low Po2 of 30mmHgPo2 of 30mmHg

a. Fetal hemoglobina. Fetal hemoglobin b. Hemoglobin concentration of fetal blood is 50% b. Hemoglobin concentration of fetal blood is 50%

greater than maternal bloodgreater than maternal blood c. Double Bohrs effectc. Double Bohrs effect

2.Diffusion of carbon dioxide through the 2.Diffusion of carbon dioxide through the placental membraneplacental membrane

- CO2 is continually being formed in fetal - CO2 is continually being formed in fetal tissuestissues

- Pco2 of fetal blood is 2 to 3mmHg higher - Pco2 of fetal blood is 2 to 3mmHg higher than maternal bloodthan maternal blood

-This small pressure gradient is more than -This small pressure gradient is more than sufficient to cause diffusion of CO2sufficient to cause diffusion of CO2

-Solubility of CO2 in placental membrane is 20 -Solubility of CO2 in placental membrane is 20 times more than solubility of oxygentimes more than solubility of oxygen

3.Diffusion of food stuffs through the placenta3.Diffusion of food stuffs through the placenta

-Diffusion is same as that of oxygen-Diffusion is same as that of oxygen

-Facilitated diffusion of glucose occurs via -Facilitated diffusion of glucose occurs via placental membraneplacental membrane

-Glucose level in fetal blood is 20 to 30% less -Glucose level in fetal blood is 20 to 30% less than maternal bloodthan maternal blood

-High solubility of fatty acids facilitates their -High solubility of fatty acids facilitates their diffusion across the placental membranediffusion across the placental membrane

- Potassium, sodium and chloride ions diffuse - Potassium, sodium and chloride ions diffuse with relative ease from maternal blood to fetal with relative ease from maternal blood to fetal bloodblood

4.Excretion of waste products through the 4.Excretion of waste products through the placental membraneplacental membrane

-The excretory products from fetal blood -The excretory products from fetal blood diffuses through placental membrane into diffuses through placental membrane into maternal blood and are excreted along with maternal blood and are excreted along with excretory products of motherexcretory products of mother

- These include urea, uric acid and creatinine- These include urea, uric acid and creatinine

-The concentration of excretory products is -The concentration of excretory products is greater in fetal blood than in maternal bloodgreater in fetal blood than in maternal blood

Hormonal factors in pregnancyHormonal factors in pregnancy5.During pregnancy placenta forms large 5.During pregnancy placenta forms large

quantities of hormones like:quantities of hormones like:

- Human Chorionic Gonadotropin- Human Chorionic Gonadotropin

-Estrogens-Estrogens

-Progesterone-Progesterone

-Human Chorionic Somatotropins-Human Chorionic Somatotropins

HCGHCG Secreted bySecreted by syncytiotrophoblastsyncytiotrophoblast cells of fertilized ovum cells of fertilized ovum Secretion is first measured in maternal blood 8 to 9 Secretion is first measured in maternal blood 8 to 9

days after ovulationdays after ovulation Rate of secretion rises rapidly reaching maximum at Rate of secretion rises rapidly reaching maximum at

10 to 12 wks of pregnancy and then declining to lower 10 to 12 wks of pregnancy and then declining to lower value by 16 to 20 wksvalue by 16 to 20 wks

It is a glycoprotein with molecular weight of 39000It is a glycoprotein with molecular weight of 39000 It is made of It is made of άά and and ββ subunits subunits Functions like luteinizing hormoneFunctions like luteinizing hormone It can be measured in blood by It can be measured in blood by RadioimmunoassayRadioimmunoassay as as

early as 6 days after conceptionearly as 6 days after conception Its presence in the urine in early pregnancy is basis of Its presence in the urine in early pregnancy is basis of

pregnancy test. It can be detected in urine as early as pregnancy test. It can be detected in urine as early as 14 days after conception14 days after conception

Functions of HCG:Functions of HCG: -prevents involution of corpus luteum-prevents involution of corpus luteum -causes corpus luteum to secrete extra -causes corpus luteum to secrete extra

quantities of estrogen and progesteronequantities of estrogen and progesterone -these hormones help in continuation of -these hormones help in continuation of

pregnancy by preventing menstruation and pregnancy by preventing menstruation and converting endometrial cells into decidual cellsconverting endometrial cells into decidual cells

-it maintains corpus luteum till placenta starts -it maintains corpus luteum till placenta starts secreting sufficient quantities of estrogen and secreting sufficient quantities of estrogen and progesteroneprogesterone

-it also exerts interstitial cell-stimulating effect -it also exerts interstitial cell-stimulating effect on testes of male fetus to secrete testosterone on testes of male fetus to secrete testosterone which causes fetus to grow male sex organswhich causes fetus to grow male sex organs

Pregnancy testsPregnancy tests 1.Immunological tests:1.Immunological tests: Principle:Principle: antiserum to HCG can detect the presence of antiserum to HCG can detect the presence of

HCG in urine and serum of pregnant women by HCG in urine and serum of pregnant women by Complement fixation test, Haemagglutination, Complement fixation test, Haemagglutination, Precipitin test.Precipitin test.

Procedure:Procedure: the presence of HCG is detected by an the presence of HCG is detected by an immunological reaction between HCG adsorbed on immunological reaction between HCG adsorbed on latex particles and HCG antiserum.latex particles and HCG antiserum.

a .A drop of urine of non-pregnant women (contains no a .A drop of urine of non-pregnant women (contains no HCG) +a drop of HCG antiserum (contains HCG HCG) +a drop of HCG antiserum (contains HCG antibodies) leads to no neutralization of HCG antibodies) leads to no neutralization of HCG antiserum, so will produce agglutination when mixed antiserum, so will produce agglutination when mixed with HCG- coated latexwith HCG- coated latex

b .A drop of urine from a pregnant women (contains HCG)+ a b .A drop of urine from a pregnant women (contains HCG)+ a drop of HCG antiserum leads to neutralization of antiserum HCG drop of HCG antiserum leads to neutralization of antiserum HCG therefore will produce agglutination when mixed with HCG therefore will produce agglutination when mixed with HCG coated latexcoated latex

2. Measurement of HCG in blood by Radioimmunoassay2. Measurement of HCG in blood by Radioimmunoassay - Antibody for HCG is prepared in a lower animal- Antibody for HCG is prepared in a lower animal -Mixture of fluid in which hormone is to be measured + small -Mixture of fluid in which hormone is to be measured + small

quantity of antibody+ HCG tagged with radioactive isotope is quantity of antibody+ HCG tagged with radioactive isotope is mademade

-The sample HCG and the tagged HCG compete for binding sites -The sample HCG and the tagged HCG compete for binding sites on antibodyon antibody

-After binding has reached equilibrium antibody-hormone is -After binding has reached equilibrium antibody-hormone is separated and measured by radioactive counting techniqueseparated and measured by radioactive counting technique

EstrogenEstrogen Secreted by Secreted by syncytiotrophoblast cellssyncytiotrophoblast cells of placenta of placenta Secretion increases 30 times the maternal level Secretion increases 30 times the maternal level

towards end of pregnancytowards end of pregnancy It causes enlargement of mothers uterusIt causes enlargement of mothers uterus Enlargement of mothers breast and breast ductal Enlargement of mothers breast and breast ductal

systemsystem Enlargement of mothers female external genetaliaEnlargement of mothers female external genetalia Relaxes pelvic ligaments of mother to make more Relaxes pelvic ligaments of mother to make more

room for growing fetusroom for growing fetus It also helps overall development of fetus during It also helps overall development of fetus during

pregnancypregnancy

ProgesteroneProgesterone Secreted by Secreted by syncytiotrophoblast cellssyncytiotrophoblast cells of placenta of placenta There is 10 fold increase in its secretion throughout There is 10 fold increase in its secretion throughout

pregnancypregnancy It helps in nutrition of morula and blastocyst by It helps in nutrition of morula and blastocyst by

increasing secretions of fallopian tubes and uterusincreasing secretions of fallopian tubes and uterus It cause decidual cells to develop in endometriumIt cause decidual cells to develop in endometrium It decreases contractility of uterus preventing It decreases contractility of uterus preventing

spontaneous abortionspontaneous abortion It helps estrogen prepare mothers breast for lactationIt helps estrogen prepare mothers breast for lactation

Human Chorionic Somatomammo Human Chorionic Somatomammo tropintropin

It is a protein having mol wt of 38000It is a protein having mol wt of 38000 Secreted by placenta at about 5Secreted by placenta at about 5thth wk of wk of

pregnancy and its secretion gradually increases pregnancy and its secretion gradually increases throughout pregnancythroughout pregnancy

It helps in development of breast and lactationIt helps in development of breast and lactation It has weak action similar to growth hormoneIt has weak action similar to growth hormone It causes decreased insulin sensitivity and It causes decreased insulin sensitivity and

utilization of glucose in mother thereby making utilization of glucose in mother thereby making large amounts of glucose available for fetuslarge amounts of glucose available for fetus

Other Hormonal factors in Other Hormonal factors in pregnancypregnancy

Pituitary secretion:Pituitary secretion: pituitary secretion of pituitary secretion of corticotropin, thyrotropin and prolactin increases. corticotropin, thyrotropin and prolactin increases. Secretion of FSH and LH decreases Secretion of FSH and LH decreases

Corticosteroid secretion:Corticosteroid secretion: increase in glucocorticoid increase in glucocorticoid secretion and aldosterone secretionsecretion and aldosterone secretion

Thyroid secretion:Thyroid secretion: mothers thyroid gland enlarges mothers thyroid gland enlarges upto 50% and secretion of thyroxine also increases upto 50% and secretion of thyroxine also increases upto 50%upto 50%

Parathyroid secretion:Parathyroid secretion: increase in secretion of increase in secretion of parathyroid hormone during pregnancy and lactationparathyroid hormone during pregnancy and lactation

Relaxin secretion:Relaxin secretion: causes relaxation of pelvic causes relaxation of pelvic ligamentsligaments

Fetoplacental unitFetoplacental unit The fetus and placenta interact in formation of steroid The fetus and placenta interact in formation of steroid

hormoneshormones The placenta synthesizes pregnenolone and progesterone The placenta synthesizes pregnenolone and progesterone

from cholesterolfrom cholesterol Progesterone enters fetal circulation and gets converted Progesterone enters fetal circulation and gets converted

into Cortisol and corticosteroneinto Cortisol and corticosterone Pregnenolone enters fetus to form Pregnenolone enters fetus to form

dehydroepiandrosterone sulphate (DHEAS ) and 16-dehydroepiandrosterone sulphate (DHEAS ) and 16-hydroxy dehydroepiandrosterone sulphate (16-hydroxy dehydroepiandrosterone sulphate (16-OHDHEAS)OHDHEAS)

DHEAS and 16-OHDHEAS are transported back to DHEAS and 16-OHDHEAS are transported back to placenta to form estradiol and estriolplacenta to form estradiol and estriol

PLACENTAPLACENTA FETAL ADRENALFETAL ADRENAL

CHOLESTEROL

PREGNENOLONE

PROGESTERONE

ESTRADIOL

ESTRIOL

DHEAS

16-OHDHEAS

CORTISOL

CORTICOSTERONE

DHEAS

16-OHDHEAS

Response of mothers body to Response of mothers body to pregnancypregnancy

Weight gainWeight gain:: the average weight gain is 24 the average weight gain is 24 pounds pounds

-7 pounds is fetus -7 pounds is fetus

-4 pounds is amniotic fluid-4 pounds is amniotic fluid

-2 pounds uterus-2 pounds uterus

-2 pounds breast-2 pounds breast

-9 pounds increase in mothers weight out of -9 pounds increase in mothers weight out of which 6 pounds are of extra cellular fluid and 3 which 6 pounds are of extra cellular fluid and 3 pounds of fat accumulation pounds of fat accumulation

Metabolism during pregnancy:Metabolism during pregnancy: -BMR increases by 15% during latter half of -BMR increases by 15% during latter half of

pregnancy due to increased secretion of Thyroxine, pregnancy due to increased secretion of Thyroxine, Adrenal Cortical hormones and sex hormonesAdrenal Cortical hormones and sex hormones

-nutritional requirements increase most being in 3-nutritional requirements increase most being in 3rdrd trimestertrimester

-greatest growth of fetus occurs in 3-greatest growth of fetus occurs in 3rdrd trimester trimester -if appropriate nutritional elements are not present in -if appropriate nutritional elements are not present in

pregnant women's diet a number of nutritional pregnant women's diet a number of nutritional deficiencies can occurdeficiencies can occur

Changes in maternal circulatory system:Changes in maternal circulatory system:

-625ml of blood flows through the maternal -625ml of blood flows through the maternal circulation of placenta each minute during last circulation of placenta each minute during last month of pregnancymonth of pregnancy

-cardiac output of mother increases by 30 to -cardiac output of mother increases by 30 to 40% by 2740% by 27thth wk of pregnancy and falls only a wk of pregnancy and falls only a little by end of pregnancylittle by end of pregnancy

-maternal blood volume increases to 30% till -maternal blood volume increases to 30% till term the increase is more towards second half term the increase is more towards second half of pregnancy. The cause is mainly hormones of pregnancy. The cause is mainly hormones like aldosterone and estrogen causing retention like aldosterone and estrogen causing retention of fluid by kidneysof fluid by kidneys

Changes in maternal respiration:Changes in maternal respiration: -due to increased BMR the amount of oxygen -due to increased BMR the amount of oxygen

used increases to 20% above normalused increases to 20% above normal -mothers minute ventilation increases to about -mothers minute ventilation increases to about

50%50% -increased levels of progesterone during -increased levels of progesterone during

pregnancy increase sensitivity of respiratory pregnancy increase sensitivity of respiratory centre to carbon dioxide thus increasing centre to carbon dioxide thus increasing minute ventilationminute ventilation

-the growing fetus decreases the diaphragm -the growing fetus decreases the diaphragm movements so the respiratory rate is increased movements so the respiratory rate is increased to maintain extra ventilationto maintain extra ventilation

Changes in maternal urinary system:Changes in maternal urinary system:

-the rate of urine formation is increased due to -the rate of urine formation is increased due to increased intake and increased load of increased intake and increased load of excretory productsexcretory products

-reabsorptive capacity for sodium, chloride -reabsorptive capacity for sodium, chloride and water by renal tubules increases by 50% and water by renal tubules increases by 50% due to production of steroid hormones by due to production of steroid hormones by placenta and adrenal cortexplacenta and adrenal cortex

-GFR also increases by 50%which increases the -GFR also increases by 50%which increases the rate of water and electrolyte excretion in urinerate of water and electrolyte excretion in urine

Amniotic fluid and its formation:Amniotic fluid and its formation: -volume is 500ml to 1 liter-volume is 500ml to 1 liter

-water in amniotic fluid is replaced every 3 hrs-water in amniotic fluid is replaced every 3 hrs

-electrolytes are replaced every 15 hrs-electrolytes are replaced every 15 hrs

-a portion of fluid is derived from renal excretion -a portion of fluid is derived from renal excretion of fetusof fetus

-the total volume is regulated by amniotic -the total volume is regulated by amniotic membranes and fetal excretionmembranes and fetal excretion

Toxemia of pregnancy:Toxemia of pregnancy: -about 5% of pregnant women have raised BP during -about 5% of pregnant women have raised BP during

last few months of pregnancylast few months of pregnancy -leakage of large amount of proteins in urine-leakage of large amount of proteins in urine -also called as -also called as Pre EclampsiaPre Eclampsia -there is excess of salt and water retention by mothers -there is excess of salt and water retention by mothers

kidneyskidneys -arterial spasm occurs in kidneys ,liver and brain-arterial spasm occurs in kidneys ,liver and brain -renal blood flow and GFR both are decreased-renal blood flow and GFR both are decreased --Eclampsia Eclampsia is similar condition with extreme degree of is similar condition with extreme degree of

vascular spasm throughout the body leading to vascular spasm throughout the body leading to seizuresseizures

-without treatment fetal and maternal mortality -without treatment fetal and maternal mortality increasesincreases

ParturitionParturition Parturition simply means birth of babyParturition simply means birth of baby

Towards end of pregnancy uterus becomes Towards end of pregnancy uterus becomes progressively excitable until it develops strong progressively excitable until it develops strong contractions and the baby is expelledcontractions and the baby is expelled

Hormonal and progressive mechanical Hormonal and progressive mechanical changes are responsible for increased changes are responsible for increased excitability of uterusexcitability of uterus

HORMONAL FACTORSHORMONAL FACTORS

a)a) Ratio of estrogens to progesteroneRatio of estrogens to progesterone

b)b) Effect of oxytocin on the uterusEffect of oxytocin on the uterus

c)c) Effect of fetal hormones on uterusEffect of fetal hormones on uterus

Ratio of estrogens to progesteroneRatio of estrogens to progesterone Progesterone inhibits uterine contractility during pregnancyProgesterone inhibits uterine contractility during pregnancy Estrogens have definite tendency to increase uterine Estrogens have definite tendency to increase uterine

contractions. It makes uterus more excitable, increases contractions. It makes uterus more excitable, increases number of gap junctions between myometrial cells and causes number of gap junctions between myometrial cells and causes production of prostaglandinsproduction of prostaglandins

Estrogen increases oxytocin receptors in myometrium and Estrogen increases oxytocin receptors in myometrium and deciduadecidua

Both estrogen and progesterone are secreted in progressively Both estrogen and progesterone are secreted in progressively greater quantities throughout pregnancy, but from 7greater quantities throughout pregnancy, but from 7thth month month onwards estrogen secretion continues but secretion of onwards estrogen secretion continues but secretion of progesterone remains constant or decreases slightlyprogesterone remains constant or decreases slightly

Estrogen to progesterone ratio increases sufficiently towards Estrogen to progesterone ratio increases sufficiently towards end of pregnancy increasing contractility of uterusend of pregnancy increasing contractility of uterus

Effect of oxytocin on uterusEffect of oxytocin on uterus Oxytocin is secreted by neurohypophysis that Oxytocin is secreted by neurohypophysis that

specifically causes uterine contractionsspecifically causes uterine contractions The uterine muscles increases its oxytocin receptors The uterine muscles increases its oxytocin receptors

during latter few months of pregnancyduring latter few months of pregnancy The rate of secretion of oxytocin increases during The rate of secretion of oxytocin increases during

laborlabor Labor is prolonged in hypophysectomized animals Labor is prolonged in hypophysectomized animals Experiments in animals indicate that irritation or Experiments in animals indicate that irritation or

stretching of cervix increases secretion of oxytocinstretching of cervix increases secretion of oxytocin

INCREASE IN OXYTOCIN RECEPTORSINCREASE IN OXYTOCIN RECEPTORS

PROSTAGLANDINSPROSTAGLANDINS

UTERINE CONTRACTIONSUTERINE CONTRACTIONS

DILATATION OF CERVIX ANDDILATATION OF CERVIX AND

DISTENTION OF VAGINADISTENTION OF VAGINA

STIMULI FROM CERVIX STIMULI FROM CERVIX

AND VAGINAAND VAGINA

INCREASED SECRETIONINCREASED SECRETION

OF OXYTOCINOF OXYTOCIN

Effect of fetal hormones on uterusEffect of fetal hormones on uterus The fetus pituitary gland secretes increasing The fetus pituitary gland secretes increasing

quantities of oxytocin that could increase quantities of oxytocin that could increase uterine contractionsuterine contractions

The fetus adrenal glands secrete large The fetus adrenal glands secrete large quantities of Cortisol which is also a uterine quantities of Cortisol which is also a uterine stimulantstimulant

The fetal membranes release prostaglandins in The fetal membranes release prostaglandins in high concentration at time of labor. This also high concentration at time of labor. This also increases the uterine contractionsincreases the uterine contractions

Mechanical factorsMechanical factors a. a. Stretch of uterine musculatureStretch of uterine musculature:: -simply stretching smooth muscle organs -simply stretching smooth muscle organs

increases their contractilityincreases their contractility

-Intermittent stretch of uterus by movements -Intermittent stretch of uterus by movements of fetus elicits smooth muscle contractionsof fetus elicits smooth muscle contractions

-twins are born on an average 19 days earlier -twins are born on an average 19 days earlier than single child emphasizes the importance of than single child emphasizes the importance of mechanical stretchmechanical stretch

b. b. Stretch or irritation of the cervix:Stretch or irritation of the cervix: - - stretching of uterine cervix is very important in stretching of uterine cervix is very important in

eliciting uterine contractionseliciting uterine contractions -to induce labor obstetricians rupture the -to induce labor obstetricians rupture the

membranes so that the head of baby stretches the membranes so that the head of baby stretches the cervixcervix

-The mechanism by which cervical irritation -The mechanism by which cervical irritation excites uterus is not knownexcites uterus is not known

-stretching or irritation of nerves in cervix -stretching or irritation of nerves in cervix initiates reflexes to the body of uterusinitiates reflexes to the body of uterus

-it can also simply be due to myogenic -it can also simply be due to myogenic transmission of signals from cervix to uterustransmission of signals from cervix to uterus

Onset of laborOnset of labor A positive feedback theory:A positive feedback theory: -Braxton hicks contractions- weak and slow rhythmical -Braxton hicks contractions- weak and slow rhythmical

contractionscontractions -Labor contractions- stronger contractions towards end of -Labor contractions- stronger contractions towards end of

pregnancypregnancy -Positive feedback theory suggests that stretching of cervix by -Positive feedback theory suggests that stretching of cervix by

fetal head finally becomes great enough to elicit a strong reflex fetal head finally becomes great enough to elicit a strong reflex increase in contractility of uterine body. This pushes the baby increase in contractility of uterine body. This pushes the baby forward which stretches the cervix even more and initiates forward which stretches the cervix even more and initiates more positive feedback to uterusmore positive feedback to uterus

-Labor contractions obey all principles of positive feedback-Labor contractions obey all principles of positive feedback -The positive feedback increases due to cervical stretching and -The positive feedback increases due to cervical stretching and

secretion of oxytocinsecretion of oxytocin -Labor contractions elicit neurogenic reflexes in spinal cord to -Labor contractions elicit neurogenic reflexes in spinal cord to

abdominal muscles causing intense contractions of these abdominal muscles causing intense contractions of these musclesmuscles

Mechanics of parturitionMechanics of parturition The uterine contractions during labor begin at top of The uterine contractions during labor begin at top of

fundus and spreads over the body of uterusfundus and spreads over the body of uterus The intensity of contractions is maximum at fundus The intensity of contractions is maximum at fundus

and body and minimum at lower segment adjacent to and body and minimum at lower segment adjacent to cervix, therefore each contractions pushing baby cervix, therefore each contractions pushing baby down towards cervixdown towards cervix

The frequency and intensity of contractions keeps on The frequency and intensity of contractions keeps on increasing with short relaxation between contractionsincreasing with short relaxation between contractions

The combined uterine and abdominal contractions The combined uterine and abdominal contractions cause a downward force of 25 pounds on fetus during cause a downward force of 25 pounds on fetus during each strong contractioneach strong contraction

The labor contractions are intermittent because strong The labor contractions are intermittent because strong contractions impede blood supply to placenta and can contractions impede blood supply to placenta and can lead to death of fetus if continuouslead to death of fetus if continuous

The head of fetus is first to be expelled in most cases. The head of fetus is first to be expelled in most cases. The acts as a wedge to open structures of birth canalThe acts as a wedge to open structures of birth canal

First stage of laborFirst stage of labor involves progressive dilation of involves progressive dilation of cervix till it becomes as large as fetus head.. It lasts for cervix till it becomes as large as fetus head.. It lasts for 8 to 12 hrs8 to 12 hrs in first pregnancy, but few minutes after in first pregnancy, but few minutes after many pregnanciesmany pregnancies

Second stage of laborSecond stage of labor lasts from cervical dilation to lasts from cervical dilation to delivery of baby. It lasts for delivery of baby. It lasts for 30 min30 min in 1 in 1stst pregnancy to pregnancy to 1 min after many pregnancies1 min after many pregnancies

Separation of placentaSeparation of placenta Uterus contracts after delivery of baby for 10 Uterus contracts after delivery of baby for 10

to 45 min. This causes shearing effect between to 45 min. This causes shearing effect between uterine wall and placenta leading to separation uterine wall and placenta leading to separation of placentaof placenta

This causes opening of placental sinuses and This causes opening of placental sinuses and bleeding.bleeding.

Amount of blood loss is 350mlAmount of blood loss is 350ml The contraction of uterus and prostaglandins The contraction of uterus and prostaglandins

released cause the blood vessels to constrict released cause the blood vessels to constrict and prevent excessive blood lossand prevent excessive blood loss

Labor painsLabor pains The painful uterine contractions during laborThe painful uterine contractions during labor It is caused by hypoxia of uterine muscles It is caused by hypoxia of uterine muscles

resulting from compression of blood vesselsresulting from compression of blood vessels Hypogastric nerves which carry visceral Hypogastric nerves which carry visceral

sensory fibers from uterus are responsible sensory fibers from uterus are responsible During second stage of labor cervical During second stage of labor cervical

stretching, perineal stretching and stretching stretching, perineal stretching and stretching and tearing of structures of vaginal canal cause and tearing of structures of vaginal canal cause painpain

Involution of uterusInvolution of uterus It takes 4 to 5 wks after parturition for uterus to come It takes 4 to 5 wks after parturition for uterus to come

back to its normal size. This is called as back to its normal size. This is called as involutioninvolution If mother lactates its size becomes as small as it was If mother lactates its size becomes as small as it was

before pregnancybefore pregnancy This happens due to suppression of pituitary This happens due to suppression of pituitary

Gonadotropin and ovarian hormone secretion during Gonadotropin and ovarian hormone secretion during first few months of lactationfirst few months of lactation

During involution lochia a vaginal discharge is During involution lochia a vaginal discharge is produced for 10 days which is bloody to start with and produced for 10 days which is bloody to start with and then serous in naturethen serous in nature

After this endometrium becomes re-epithelialized and After this endometrium becomes re-epithelialized and returns to normalreturns to normal

LactationLactationLactation includes:Lactation includes:

1.Development of breast- function of 1.Development of breast- function of estrogens and progesteroneestrogens and progesterone

2.Initiation of lactation- function of prolactin2.Initiation of lactation- function of prolactin

3.Ejection (let down ) process in milk 3.Ejection (let down ) process in milk secretion- function of oxytocinsecretion- function of oxytocin

Development of breastDevelopment of breast This involves:This involves:

1.Growth of ductal system-role of estrogens:1.Growth of ductal system-role of estrogens:

-Tremendous quantities of estrogens secreted -Tremendous quantities of estrogens secreted by placenta during pregnancy cause ductal by placenta during pregnancy cause ductal system of breast to branch and growsystem of breast to branch and grow

-Stroma of breast also increases with -Stroma of breast also increases with deposition of fatdeposition of fat

-Other hormones responsible are GH, -Other hormones responsible are GH, Prolactin, Adrenal glucocorticoids and InsulinProlactin, Adrenal glucocorticoids and Insulin

2.Development of lobule -alveolar system—Role 2.Development of lobule -alveolar system—Role of progesteroneof progesterone

- Final development of breasts into milk - Final development of breasts into milk secreting organs requires progesteronesecreting organs requires progesterone

-Progesterone acts synergistically with other -Progesterone acts synergistically with other hormones like estrogen to cause additional hormones like estrogen to cause additional growth of breast lobules, budding of alveoli and growth of breast lobules, budding of alveoli and development of secretory characteristics in cells development of secretory characteristics in cells of alveoliof alveoli

-These changes are analogous to effects of -These changes are analogous to effects of progesterone on uterine endometriumprogesterone on uterine endometrium

Initiation of lactation-function of Initiation of lactation-function of prolactinprolactin

- Prolactin is secreted by ant pituitary gland- Prolactin is secreted by ant pituitary gland - It promotes milk secretion- It promotes milk secretion - Its concentration increases in blood after 5- Its concentration increases in blood after 5thth wk of pregnancy wk of pregnancy

until birth of baby when it is 10 to 20 times non pregnant leveluntil birth of baby when it is 10 to 20 times non pregnant level - Estrogen and progesterone though imp for breast development - Estrogen and progesterone though imp for breast development

also inhibit the actual secretion of milkalso inhibit the actual secretion of milk -HCG secreted by placenta also has lactogenic properties-HCG secreted by placenta also has lactogenic properties --ColostrumColostrum is fluid secreted in last few days before and first few is fluid secreted in last few days before and first few

days after parturitiondays after parturition -It has same concentration of glucose and proteins like milk but -It has same concentration of glucose and proteins like milk but

no fatno fat

-After the birth of baby, there is sudden fall in -After the birth of baby, there is sudden fall in concentration of estrogens and progesterone. This concentration of estrogens and progesterone. This allows prolactin to take over its natural milk allows prolactin to take over its natural milk promoting rolepromoting role

-This milk secretion also requires adequate background -This milk secretion also requires adequate background secretion of hormones like GH, Cortisol, Parathyroid secretion of hormones like GH, Cortisol, Parathyroid hormone and Insulinhormone and Insulin

-These provide amino-acids, glucose, fatty acids and -These provide amino-acids, glucose, fatty acids and calcium required for milk formationcalcium required for milk formation

-After birth of baby the basal level of prolactin -After birth of baby the basal level of prolactin secretion returns to non pregnant level after a few secretion returns to non pregnant level after a few weeksweeks

-Each time mother nurses child nervous signals from -Each time mother nurses child nervous signals from nipple to hypothalamus cause 10 to 20 fold surge in nipple to hypothalamus cause 10 to 20 fold surge in prolactin secretion which lasts for about 1hrprolactin secretion which lasts for about 1hr

Hypothalamic control of prolactin Hypothalamic control of prolactin secretionsecretion

Hypothalamus plays important role in Hypothalamus plays important role in prolactin productionprolactin production

It mainly inhibits prolactin productionIt mainly inhibits prolactin production This is done by This is done by prolactin inhibitory hormoneprolactin inhibitory hormone

secreted by Arcuate nucleus of hypothalamussecreted by Arcuate nucleus of hypothalamus It can decrease prolactin secretion upto 10 foldIt can decrease prolactin secretion upto 10 fold It also secretes a It also secretes a Prolactin releasing factorProlactin releasing factor

which intermittently increases prolactin which intermittently increases prolactin secretion( under special conditions when baby secretion( under special conditions when baby suckles)suckles)

Effect of lactation on menstrual Effect of lactation on menstrual cycle cycle

Women who do not nurse their infants usually have their periods Women who do not nurse their infants usually have their periods by 6 wks after deliveryby 6 wks after delivery

Women who nurse regularly have amenorrhea for 25-30 wksWomen who nurse regularly have amenorrhea for 25-30 wks Nursing stimulates prolactin secretion which inhibits GnRH Nursing stimulates prolactin secretion which inhibits GnRH

secretion, inhibits the action of GnRH on pituitary, and secretion, inhibits the action of GnRH on pituitary, and antagonizes action of gonadotropins on ovariesantagonizes action of gonadotropins on ovaries

This suppresses secretion of FSH and LHThis suppresses secretion of FSH and LH Ovulation and ovarian cycle are inhibited and ovaries are Ovulation and ovarian cycle are inhibited and ovaries are

inactive, so estrogen and progesterone output falls to low levelsinactive, so estrogen and progesterone output falls to low levels Also 50% of cycles in first 6 months after resumption of mensus Also 50% of cycles in first 6 months after resumption of mensus

are anovulatoryare anovulatory

Ejection ( let-down ) process in milk Ejection ( let-down ) process in milk secretion – function of oxytocinsecretion – function of oxytocin

Milk that is secreted continuously in alveoli of breast does not Milk that is secreted continuously in alveoli of breast does not flow easily into ductal systemflow easily into ductal system

The milk must be ejected from alveoli into ducts before the The milk must be ejected from alveoli into ducts before the baby can obtain itbaby can obtain it

This ejection is caused by aThis ejection is caused by a neurogenic neurogenic and and hormonal reflexhormonal reflex that involves oxytocin hormonethat involves oxytocin hormone

When baby suckles sensory impulses are transmitted via When baby suckles sensory impulses are transmitted via somatic nerves from nipples to mothers spinal cord and then to somatic nerves from nipples to mothers spinal cord and then to hypothalamushypothalamus

This causes secretion of oxytocin and prolactinThis causes secretion of oxytocin and prolactin The oxytocin is carried in blood to breasts where it causes The oxytocin is carried in blood to breasts where it causes

myoepithelial cells to contract thereby expressing milk from myoepithelial cells to contract thereby expressing milk from alveoli into ductsalveoli into ducts

Within Within 30sec to 1min30sec to 1min after baby begins to suckle, milk begins to after baby begins to suckle, milk begins to flow flow

Composition of milkComposition of milk

HUMAN MILK(%)

COWS MILK(%)

WATERFAT

LACTOSE

CASEIN

LACTALBUMIN AND OTHER PROTEINS

ASH

88.5

3.3

6.8

0.9

0.4

0.2

87.0

3.5

4.8

2.7

0.7

0.7

Lactation – metabolic drain on Lactation – metabolic drain on mothermother

At the height of lactation in human mother 1.5 At the height of lactation in human mother 1.5 liters of milk is formed everydayliters of milk is formed everyday

At this rate about, 50gms of fat, 100gms of At this rate about, 50gms of fat, 100gms of lactose and 2 to 3gms of calcium phosphate lactose and 2 to 3gms of calcium phosphate enter the milk everydayenter the milk everyday

This is a great metabolic drain on mothers This is a great metabolic drain on mothers bodybody

The nursing mother should have nutritious The nursing mother should have nutritious diet to maintain adequate nutrition of her diet to maintain adequate nutrition of her bodybody

Antibodies and other Anti-infectious Antibodies and other Anti-infectious Agents in MilkAgents in Milk

Mothers milk provides the baby with adequate Mothers milk provides the baby with adequate nutrition and also provides protection against nutrition and also provides protection against infectionsinfections

Many antibodies and anti-infectious agents are Many antibodies and anti-infectious agents are secreted in milksecreted in milk

Different types of white blood cells like Different types of white blood cells like neutrophils and macrophages are secreted neutrophils and macrophages are secreted which prevent child from deadly bacterial which prevent child from deadly bacterial infectionsinfections