2. Early intra-uterine nutrition
Persistence of CL and continued secretion of progesterone causes excessive deposition of nutrients and swelling in the endometrial stromal cells
Decidual cells
Trophoblasts digest and imbibe these nutrients in the decidua

3. Early intra-uterine nutrition
This is the only way of nutrition in 1st week after implantation
Placenta starts supplying nutrition on about 16th day of fertilization
Trophoblastic nutrition continues for 8th week of pregnancy

4. Placenta Trophoblastic cord grow and branch deep into the endometrium
Fetal blood vessels grow into these cord
Blood begins to flow on about 16th day of fertilization
The final branches of the trophoblastic cords form placental villi
Maternal blood sinuses surround these villi

5. Placenta

6. Placental membrane Consists of Total surface area- a few square meters
Endothelium of the fetal capillaries
Mesencymal tissue
Layer of Cytotrophoblasts (early stages of placental development)
Layer of Syncytial trophoblasts
Total surface area- a few square meters
Thickness- 3.5 micrometer
Diffusion across the placental membrane
Nutrients and other requirements to the fetus
Waste products from the fetus into the mother

7. Placental permeability & conductance
Net quantity of substance diffusing through the placental membrane /unit SA for a given concentration gradient across the placental membrane
Total conductance
Permeability X Total SA
Early pregnancy
Permeability very low
Less surface area
Thick placental membrane
Later pregnancy
Tremendous permeability and total conductance

8. Placental conductance

9. Diffusion of O2 Mean pO2 in maternal blood = 50 mm Hg
Mean pO2 in fetal oxygenated blood= 30 mm Hg
Mean pressure gradient across the placental membrane = 20 mm Hg
O2 diffusing capacity= 1.2 ml/min
Fetal oxygenated blood pO2 of only 30 mm Hg sufficient to supply required O2 to fetus because
HbF has more O2 carrying capacity
Hb concentration is 50% more than adult
Double Bohr effect across the placental membrane
Oxygen carrying capacity is inversely proportional to Pco2

10. HbF carries more O2

11. Diffusion of CO2 CO2 continuously formed in the fetus
Fetal lungs nonfunctional
CO2 must be excreted through maternal lungs
Estrogen and progesterone affect maternal breathing to eliminate more CO2
pCO2 in maternal blood = 40 mm Hg
pCO2 in fetal blood is always 2-3 mm Hg higher than maternal blood
20 times more rapid diffusion than O2

12. Crossing of other substances
Food stuffs
Diffusion – FA, Ketone bodies, Na, K, Cl
Facilitated diffusion – glucose
Active transport – AA, Ca, PO4, ascorbic acid
Waste products of fetus other than CO2
Diffusion - Urea, Uric acid, creatinine

13. Hormonal factors Pregnancy

14. Hormones of placenta Five important hormones
Human chorionic gonadotrophic hormone (HCGH)
Estrogen
Progesterone
Human chorionic somatomammotrophic hormone
Relaxin

15. Human chorionic gonadotrophic hormone (HCGH)
Involution of Corpus Luteum occurs on 12th day after ovulation
Menstruation occurs after 14th day of ovulation
This has to be prevented if fertilized ovum has implanted
HCG is the earliest placental hormone
Secreted by Syncytial trophoblasts
8-9 day after ovulation

16. Human chorionic gonadotrophic hormone (HCGH)
A glycoprotein
MW = 39000
Functions similar to LH
Most important
Prevention of involution of CL and menstruation
Continued production of estrogen and progesterone from CL for a few months
Estrogen and progesterone cause continued growth of endometrium
Formation of Decidual cells for early nutrition of the fetus

17. Human chorionic gonadotrophic hormone (HCGH)
Removal of CL before 7th week of pregnancy → Spontaneous abortion
Removal after 12th week → no abortion
Placental Estrogen and progesterone are sufficient to maintain pregnancy
CL of pregnancy slowly involutes between 13th to 17th week of gestation

18. Hormones in pregnancy

19. (HCGH) and fetal testes
HCG similar to LH (ICSH)
Stimulates fetal testicular interstitial cell of Leydig
Production of testosterone
Intrauterine functions of testosterone
Development of male genitalia
Descent of testes

20. Placental estrogen Secreted by Syncytial trophoblasts
Level 30 times the non-gravid level
Not synthesized de novo from acetate or cholesterol in the placenta
Androgens from Adrenal cortex of mother and fetus are converted into estrogens
Dehydroepiandrosterone
16-hydoxydehydoepiandrosterone
Estriol is the most abundant amongst the placental estrogens

21. Functions of placental estrogen
Estriol has weaker estrogenic potency than ovarian β-estradiol
Functions of estrogens
Enlargement of uterus
Proliferation of endometrium
Enlargement of breasts
Laying down of ductile system of mammary gland
Enlargement of external genitalia

22. Functions of placental estrogen
Deposition of fats through out the adipose tissue
Salt and water conservation by the kidneys
Relaxation of pelvic ligaments
Sacroiliac joint
Pubic symphysis
for easy passage of fetus during labor through birth canal

23. Placental progesterone
Level about 10 times the non-gravid level
Synthesis from adrenal androgens
Functions
Development of Decidual cells
Increased secretion of FT and endometrial glands
Reduced contractility of the uterus
Development of alveoli and lobules of the mammary gland
Final preparation the breasts for lactation

24. Human chorionic somatomammotrophic hormone
Protein in nature
MW = 38000
Secretion starts in 5th week
Increases through out the pregnancy
Causes development of breast for lactation
(actual milk secretion in some lower animals)
Initially named as placental lactogen
Growth hormone like action (much weaker than GH)
↓ insulin sensitivity of maternal tissues → ↓ utilization of glucose by the mother
Mobilization of FA for mother and fetus both

25. Hormonal Secretion by the Placenta

26. Other endocrine glands in pregnancy
Pituitary
↑ ACTH, TSH, Prolactin
↓ FSH, LH
Adrenal cortex
↑Cortisol, Aldosterone, androgens
Thyroid gland
↑ T3, T4
Parathyroid gland
↑ parathyroid hormone
Ovaries
↑ estrogen and progesterone form CL
Secretion of relaxin
Polypeptide of 9000 MW
Also produced by placenta
Causes relaxation of the pelvic ligaments

27. Response of the mother’s body to Pregnancy
↑ size of the reproductive organs
Uterus increases from 50 gm to 1100 gm
Breast double in size
Enlargement of vagina and wider opening of the introitus
Different changes in general appearance may occur
Edema – salt and water retention
Acne – excessive androgenic hormones
Masculine features – excessive androgenic activity
Acromegalic features – ↑GH, HCSMH

28. Response of the mother’s body to Pregnancy
Weight gain
Average 24 lbs
Fetus lbs
Amniotic fluid, placenta & fetal membranes 4 lbs
Uterus lbs
Breasts lbs
Salt & water and general increase 9 lbs
↑ appetite – if not controlled weight gain may be 75 lbs
Metabolism
↑Hormone → ↑ metabolism
15 % increase in BMR
More energy expenditure

29. Digestive System and nutrition
Most of the wt. gain and nutritional needs are in later part of the pregnancy
Less absorption from GIT in 3rd trimester
Early part of pregnancy – storage of nutrients in placenta and maternal tissues
Requirements increased
Carbohydrates, proteins, fats, minerals, vitamins
Iron
375 mg for fetal blood
600 mg for maternal blood
Calcium
Vitamin D
Different deficiency syndromes may develop if requirements are not fulfilled

30. Cardiovascular System
↑Blood volume – 30% above normal
↑ COP up to 27th (30-40%) week, returns to almost normal in last 8 weeks
↑ heart rate and blood pressure
Cardiovascular changes to meet needs of fetus

31. Increase in maternal blood volume

32. Respiratory System ↑ metabolism → ↑ O2 consumption ↑ CO2 production
CO2 and progesterone increase the minute ventilation -50 %
↓PCO2 compared to non- pregnant level
Diaphragm is raised
movement is restricted
rate is increased

33. Urinary System
Responsible for excretion of more metabolites due to ↑ metabolism
↑ glomerular filtration rate
↑ urine formation
↑ reabsorption of salt and water
Accumulation of extra 6 lbs of salt and water

34. Amniotic fluid Volume = 500 -1000 ml May be a few ml – several litters
Water turn over time = 3 hours
Electrolyte turn over time = 15 hours
Formed from
Secretion from amniotic vessels
Renal excretion of the fetus
Absorption into
Amniotic blood vessels
Fetal GIT

35. Toxemia of pregnancy Pre-eclampsia Causes Hypertension Albuminurea
Edema
Weight gain
Vascular spasm in many parts of the body →↓ blood flow
↓ renal blood flow →↓ GFR
Causes
Unknown
Autoimmunity to pregnancy
Allergy to pregnancy
Associated with insufficient blood flow to placenta
Cytokines – tumor necrosis factor-α, interluekin-6

36. Toxemia of pregnancy Eclampsia Treatment
Usually occurs shortly before labor
Exaggeration of all the symptoms of pre-eclampsia
Extreme vascular spasm
Convulsions
Coma
Renal failure
Hepatic failure
Mortality rate very high
Treatment
Rapidly acting vasodilators
Sedation
Termination of the pregnancy

37. Thank-you
Questions ??