1. Physiology of pregnancy. The perinatal care of the fetus.
Prepared by N. Bahniy

2. STAGES OF PRENATAL DEVELOPMENT
Preembryonic stage - first 2 weeks. Products of conception are called as conceptus.
Embryonic stage - from the third week until the end of the eight week. From this period conceptus is called embryo.
Fetal period starts from the beginning of the ninth week through the full 41 weeks of development. Products of conception are called as fetus.

3. Preembryonic Stage fertilization zygote formation
division of fertilized ovum
morula formatiom
formation of free blastocyst
implantation of the ovum in the uterine wall
Primitive chorionic villi formation
Initial folding into layers – gastrulation beginning.
Chorion and amnion begin to form during this period also.

4. A SPERM FERTILIZING AN OVUM

5. Formation of free blastocyst
Morula
From inner layer - embryoblast
From outer layer - trophoblast

6. Implantation- attachment of the blastocyst on the 7th day into uterine wall called implantation.

7. EMBRYONIC STAGE
Formation of supportive structures - include the placenta, umbilical cord, and certain extraembryonic membranes.
The yolk sac forms early and manufactures blood cells until the liver takes over at 6 week.
The allantois forms the part of the yolk sac; it produces blood cells and eventually forms the umbilical arteries and veins.
During the third week the primitive streak appears, and then, other rudiments of organs form, including the central nervous system, notochord, neural tube, heart, limbs, finger, toes, eyes, ears, and nose.

8. AN AMBRYO IS ABOUT 5 WEEKS OLD

9. "FETUS OF ABOUT EIGHT WEEKS, ENCLOSED IN THE AMNION," FROM GRAY'S ANATOMY. PART OF THE PLACENTA IS SHOWN AS THE LOWEST FEATURE IN THIS IMAGE, AND THE AMNION EXTENDS ABOVE THE FETUS.[1

10. Critical periods of fetal development
Implantation
Morphogenesis and organogenesis
Placentation

11. Growing and differentiation of the structures during the Fetal Period

12. 12

13. 13

14. Conceptus structure in the end of pregnancy
Fetus
Umbilical cord
Placenta
Amniotic Fluid
Amnion
Chorion
Decidua

15. Fetal characteristics
Classification
Gestational age (weeks of pregnancy
Weight, gram
Length, cm
Signs of maturity
“Deep pre-term fetus”
12 – 22
25 – 500
9 - 25
Absent
“Fetus pre-term”
22 –36+6 days
500 – 2500
“Fetus in-term”
37 – 41
> 2500
( ) 47
(50-52)
Present
“Fetus post-term”
> 41

16. Signs of fetal maturity
Umbilical ring is between pubis and processes xyphoideus
Pink skin
Well-developed subcutaneous tissue,
Lanugo in the shoulders and upper part of the back
Length of the hair on the head is 2 cm
Nails are present till the top of the fingers
Well-developed ears and nose cartilage
Testes are present in the scrotum in the boys and labia major are covered labia minor in the girls
Active movements
Loud cry of the infant

17. FETAL HEAD AT TERM

18. DIAMETERS OF THE FETAL HEAD AT TERM
1. The suboccipitobregmatic (9.5 cm, 32cm), which follows from the middle of the large fontanel to the undersurface of the occipital bone.
2. The suboccipitofrontalis (10cm,33 cm) – from subocipital fossa to border of the hair.
3. The occipitofrontal (12 cm, 34 cm), which follows a line extending from a point just above the root of the nose to the most prominent portion of the occipital bone.
4. The occipitomental ( cm, 39-41cm), from the chin to the most prominent portion of the occiput.
5.The sublingquobregmatica (9,5 cm, 32 cm).
6. The biparietal (9.5 cm), the greatest transverse diameter of the head, which extends from one parietal boss to the other.
7. The bitemporal (8.0 cm), the greatest distance between the two temporal sutures.

19. DIAMETERS OF THE FETAL BODY AT TERM
Biacromial distance – 12cm, cm
Bisiliacus distance – 9cm, cm

20. DECIDUA - MATERNAL MEMBRANE, immunologically specialized tissue
DECIDUA - MATERNAL MEMBRANE, immunologically specialized tissue. provides for embryo-fetal nutrition.

21. Fetal membranes Structure chorion and amnion Amnion A double-layered
translucent membrane
Become distended
with fluid

22. Amniotic fluid 1000-1500ml at 36th-38th week (peak)
Absorb
Fetal membrane
Umbilical cord
Fetal skin
Fetal drinking
Source
Fetal urine
Fetal lung
Exudation of amnion and fetal skin
Functions:
Protection of the fetus
Protect mother, prevent infection

23. Formation of the forebag

24. Umbilical Cord Structure
amnion, yolk sac, one vein, two artery and Wharton jelly
Length
30-70cm

25. Placenta at section Fetal and maternal parts. Cotyledon – is a small
compound of placenta.

26. Placental villi
At term, the placenta contains approximately 12 m2 of villous surface area for maternofetal exchange.

27. Placental functions Endocrine Transfer of nutrients
Excretory - removal
of the products of fetal catabolism
Barrier
Oxygen-transport

28. Placental hormones 1. Protein hormones of the placenta:
chorionic gonadotropin (cHG)– it is maintain the function of the corpus luteum during early gestation, promote uterine vascular vasodilation and myometrial smooth muscle relaxation, relaxin secretion by the corpus luteum, stimulate thyroid activity, and some more basic forms also stimulate iodine uptake
human lactogen – its actions include lipolisis and an increase in the levels of circulating free fatty acids, thus providing a source of energy for maternal metabolism and fetal nutrition
2. Steroid hormones of the placenta: estrogens; progesterone.
3. Chorionic adrenocorticotropin and thyrotropin, growth hormone variant, parathyroid hormone-related protein (PTH-rP), calcitonin, and relaxin – no significant role has been established for this substance in normal human pregnancy.
4. Hypothalamic-like-releasing hormones of the placenta

29. Type of human placentation - hemochorioendothelial

30. Role of Estrogen in Pregnancy:
Increasing blood flow to the uterus by promoting vasodilation.
Changing the sensitivity of the respiratory system to carbon dioxide.
Softening of the cervix, initiating uterine activity, and maintaining labor.
Developing the breasts in preparation for lactation and secretion of prolactin by the pituitary gland.
Estrogen levels increase rapidly early in pregnancy, slow between weeks gestation and increase again toward term.
The production of estrogen is dependent on the interaction between the maternal and fetal components of the placenta.

31. Role of Progesterone in Pregnancy:
Ready the uterus for implantation.
Relaxes smooth muscle to prevent spontaneous abortion.
Works to prevent a maternal immunologic response to the fetus.
Relaxes smooth muscle
to decrease motility & improve absorption of nutrients.
Enlarges the ureters & bladder to increase capacity.
Plays a role in development of the alveoli & ductal system to prepare for lactation.

32. Physiologic changes in pregnant woman
Genital organs
Uterus
capacity: 5ml-5000ml.weight: 50g-1000g
Hypertrophy of muscle cells
Endometrium→decidua: basal decidua, capsular decidua, true decidua
Contraction: Braxton Hicks
Isthmus uteri: 1cm→ 7-10cm
Cervix: colored
Ovary: placenta replaces ovary (10th week)
Vagina: dilated and soft, pH↓(anti-bacteria)
Ligaments: relaxed

33. Physiologic changes in pregnant woman
Cardiovascular system
Heart:
move upward, hypertrophy of cardiac muscle
Cardiac Output
increase by 30%, reach to peak at 32nd –34th week
Blood pressure
early or mid pregnancy Bp↓.late pregnancy Bp↑ .Supine hypotensive syndrome

34. Physiologic changes in pregnant woman
Hematology
Blood volume
Increase by 30%-45% at 32nd –34th (peak)
Relatively diluted
Composition
Red cells
Hb:130→110g/L, HCT:38%→ 31%.
White cells: slightly increase
Coagulating power of blood: ↑
Albumin: ↓,35 g/L

35. Physiologic changes in pregnant woman
The Respiratory system
R rate: slightly ↑
vital capacity: no change
Tidal volume: ↑ 40%
Functional residual capacity:↓
O2 consumption: ↑ 20%

36. Physiologic changes in pregnant woman
Kidney
Renal plasma flow (RFP):↑35%
Glomerular filtration rate (GFR):↑ 50%
Ureter
Dilated (P↑)
Bladder
Frequent urination

37. Physiologic changes in pregnant woman
Gastrointestinal system
Gastric emptying time is prolonged→ nausea.
The motility of large bowel is diminished → constipation
Liver function: unchanged

38. Physiologic changes in pregnant woman
Endocrine
Pituitary (hypertrophy)
LH/FSH: ↓
PRL:↑
TSH and ACTH:↑
Thyroid
enlarged (TSH and HCG↑)
thyroxine↑ and TBG↑ → free T3 T4 unchanged

39. Thanks for attention