Physiology of Pregnancy

1. Physiology of Pregnancy Weirong Gu Obsterics & Gynecology Hospital of Fudan university

2. pregnancy The condition of being with child or gravid, is the process of embryo and fetus growing and developing in the uterus From the fertilization to the expelling of the fetus with placenta and membranes

3. contents • fertilization, development, transport and implantation of fertilized ovum • formation and function of fetal attachment • maternal changes during pregnancy

4. concepts sperm capacitation fertilization acrosome reaction zona reaction

5. sperm capacitation Spermatozoons contact with endometrium the α-/β- amylase remove the decapacitation factor on spermatozoons’ acrosomal enzyme the spermatozoons with the ability of fertilization(capacitation)in uterus and fallopian tubes

6. acrosome reaction Acrosome rupture, acrosomal enzyme released and lysis the radiate corona and zone pellucida The spermatozoons penetrate and fuse with oocyte

7. zona reaction the cortical particle of cytoplasm release lysosomal enzyme zona structure changed and sperm receptor degenerated to prevent other sperm into the zona

8. fertilization The course of combination of the oocyte and sperm Time : 12h after ovulation Place : usually in ampulla of the oviduct (fallopian tube)

9. development and transport of the zygote

10. implantation • Late blastosphere implanted in endometrium • Apposition • Adhesion • penetration

11. The necessary condition of implantation Disapearing of the zona pellucid Formation of syncytiotrophoblast Synchronizing development of blastocyst and endometrium Adequate progesterone

12. Changes of endomertium after implantation • The endometrium changes into dicedua • Basal decidua • Capsular decidua • Ture decidua

13. Embryo and fetal development Embryo: the first 8 weeks from pregancy Fetus: after 9 weeks from pregnancy ,human shape

14. 12 Gestational Weeks • The uterus usually is just palpable above the symphysis pubis, and the fetal crown-rump length is 6 to 7 cm. • Centers of ossification have appeared in most of the fetal bones, and the fingers and toes have become differentiated. • Skin and nails have developed and scattered rudiments of hair appear. • The external genitalia are beginning to show definitive signs of male or female gender. • The fetus begins to make spontaneous movements.

15. 16 Gestational Weeks • fetal crown-rump length: 12 cm • weight : 110 g • Gender can be determined by 14 weeks

16. 20 Gestational Weeks • Weight: more than 300 g, and increase in a linear manner • Movement: about every minute and is active 10 to 30 percent of the time • skin : less transparent, a downy lanugo covers entire body, some scalp hair has developed.

17. 24 Gestational Weeks • The fetus now weighs about 630 g. • The skin is characteristically wrinkled, and fat deposition begins. • The head is still comparatively large, and eyebrows and eyelashes are usually recognizable. • The canalicular period of lung development, during which the bronchi and bronchioles enlarge and alveolar ducts develop, is nearly completed. • A fetus born at this time will attempt to breathe, but many will die because the terminal sacs, required for gas exchange, have not yet formed.

18. 28 Gestational Weeks • The crown-rump length is approximately 25 cm, and the fetus weighs about 1100 g. • The thin skin is red and covered with vernix caseosa. • The pupillary membrane has just disappeared from the eyes. • The otherwise normal neonate born at this age has a 90-percent chance of survival without physical or neurological impairment.

19. 32 Gestational Weeks • The fetus has attained a crown-rump length of about 28 cm and a weight of approximately 1800 g. • The skin surface is still red and wrinkled.

20. 36 Gestational Weeks • The average crown-rump length of the fetus is about 32 cm, and the weight is approximately 2500 g. • Because of the deposition of subcutaneous fat, the body has become more rotund, and the previous wrinkled appearance of the face has been lost.

21. 40 Gestational Weeks • This is considered term from the onset of the last menstrual period. • The fetus is now fully developed. • The average crown-rump length is about 36 cm, and the weight is approximately 3400 g.

22. Physiology of fetus • circulation • Fetus---placenta---mother • 1 umbilical vein (full of oxygen) • 2 umbilical arteries (lack of oxygen) • Mixed blood ( vein and artery) • Ductus arteriosus • Foramen ovale • Ductus venosus

24. hematology • erythropoiesis • From yolk sac: 3 weeks • From liver: 10 weeks • From bone marrow and spleen: term (90%) • EPO production: 32nd week • Fetal blood volume:125ml/kg of the fetus at term

25. Fetal hemoglobin • Fetal hemoglobin: early pregnancy • Adult hemoglobin: 32nd week • Term : fetal type Hb 25% • White cells • Leukocytes: 8 week • Lymphocytes (antibody production): 12 week thymus and spleen

26. Fetal respiratory system The timetable of lung maturation and identification of biochemical indices of functional fetal lung maturity are important to the obstetrician A sufficient amount of surface-active materials in the amniotic fluid is evidence of fetal lung maturity Surfactant: produced by type Ⅱcells of the lung alveoli; active component is a specific lecithin or dipalmitoylphosphatidylcholine

27. Gastrointestinal tract • Swallowing begins at 10-12 weeks, 16weeks, gastrointestinal function is established • Liver • Hepatic enzyme is lack during fetal period, a very limite capacity for converting free bilirubin to conjugating bilirubin

28. Urinary system • The fetal kidneys start producing urine at 12 weeks’ gestation. 7-14ml/d by 18 weeks, 27ml/hr or 650ml/d at term • Genital system • Genital organ is developed from 9 weeks of pregnancy(male), 11-12 weeks(female)

29. Attachment of the fetal Placenta Fetal membranes Umbilical cord Amniotic fluid

30. placenta • An exchange organ between maternal and fetal • Organization • Amniotic membrane • Chorion frondosum • Basal decidua

31. Chorion frondosum • 13-21 days after ovulation, villi fomulating gradually • Primary viilus • Syncytiotrophoblast • cytotrophoblast • Secondary villus • Third class villus Fetal capillary enter the stroma

32. Structure of placenta Round Weight: 450-650g Diameter: 16-20cm Thickness: 1-3cm thick in center and thin in margin

33. Function of placenta One important function of placenta is substance exchange between maternal and fetal Transfer oxygen and nutrients from the mother to the fetus and conversely the transfer of carbon dioxide and other metabolic wastes from fetus to mother

34. The position exchange is VSM(vasculosyncytial membrane) • VSM is comprised of • Syntrophoblastocyte • Basal membrane of syntrophoblastocyte • Stroma of villi • Basal membrane of capillary • Endothelium of capillary

35. The way of substance exchange Simple diffusion Facilitated diffusion Active transportion phagocytosis

36. The function of placenta • Gas exchange • Suply of nutrition • Depletion of fetal product of metabolism • Defence function • Hormone synthesis • Human chorionic gonadotropin (HCG) • Human placental lactogen (HPL) • Pregnancy specific ß-glycoprotein (PS ß1G) • Human chorionic thyrotropin(HCT) • Estrogen, P, Oxytocinase, heat stable alkaline phosphatase(HSAP)

37. Fetal membrane • Chorion • Amnion • A double-layered translucent membrane • Become distended with fluid

38. Umbilical cord Extends from the fetal umbilicus to the fetal surface of the placenta Length: 30-70cm average : 50cm Diameter: 0.8-2.0cm Consist of 2 artery and 1 vein, Wharton jelly amnion, yolk sac

39. Amniotic fluid • Source: • early from serum dialysis • Mid-pregnancy from fetal urine • Late from fetal lung • Absorse: • fetal membrane • Umbilical cord • Fetal skin • Fetal fetal swallowing (500ml/day) • Amniotic exchange: between maternal and fetal 400ml/h • Volume: 50ml at 12 weeks, 400ml at midpregancy, 1000ml at term

40. Volume of amniotic fluid 8 weeks: 5-10ml 10 weeks: 30ml 20 weeks: 400ml 38 weeks: 1000ml

41. feature of amniotic fluid pH: 7.20 Density: 1.007-1.025 Contained: water(98-99%) inorganic substance organic substance(1-2%) Early transparent Late slighty turbid

42. The function of amniotic fluid • Protect maternal and fetus • Move freely • Warm • Protect mother • Prevent infection

43. Maternal changes during pregancy The maternal system may produce a series of changes in order to adapt to the needing of fetal growth and development influenced by placenta hormone and neuro-endorine

44. Changes of reproductive system • Uterus • Capacity : 5ml - 5000ml • Weight: 50g – 1000g • Hypertrophy of muscle cells • fundus-inferior portion-cervix • Endometrium –decidua

45. Blood supply • increases 4-6times (500-700ml/min) • Most transported to the placenta(80-85%) • Uterine contraction • Braxton hicks contraction-contraction without pain • Rare, irregular,and asymmetric • Intrauterine pressure: 5-25mmHg, duration <30s

46. Isthmus • softer and longer (1,7-10cm) lower segment • Cervix • Colored • Cerical mucus plugs

47. Maternal Physiology

48. Changes of ovary Enlarged Ovulation and new follicle is stopped. Luteum produces E and P from 7 weeks of pregnancy, but start to atrophy after 10 weeks of pregnancy, the fuction is replaced by placenta

49. Fallopian tubes: is prolonged but not hypertrophy Vagina: dilated and soft , violet coloration, desquamation of epithelium with more glycogen acidity pH (anti- bacteria) Vulva: pigmentation Ligaments: relaxed

50. breasts An increase in size and a nodular sensation due to the hypertrophy of the mammary alveoli, the nipples soon become larger, more deeply pigmented and more erectile. Scattered around the areola are some roundish nodules called Montgomery tubercles which result from the hypertrophy of the sebaceous glands