This document provides an overview of physiology of pregnancy. It defines pregnancy as beginning at fertilization and ending at delivery. Key aspects discussed include fertilization, development of the fertilized egg, implantation, changes to the endometrium after implantation, attachment of the fetal structures including the placenta, fetal membranes, umbilical cord and amniotic fluid. The functions of these structures are explained. Maternal changes during pregnancy impacting the reproductive, circulatory and blood systems are also summarized.

1. PPhhyyssiioollooggyy ooff pprreeggnnaannccyy
Zhao aimin

2. DDeeffiinniittiioonn ooff pprreeggnnaannccyy
Pregnancy is defined as the course of
embryo and fetal growth and
development in uterine
It begain at the fertilization and end the
delivery of the fetal and it’s attachment

3. DDeeffiinniittiioonn ooff ffeerrttiillaazzaattiioonn
Fertilization is defined as the course
of combination of the oocyte and
sperm
It onset 12h after ovulation usually in
ampulla of the oviduct(fallopian tube)

4. TThhee DDeevveellooppmmeenntt ooff tthhee
ffeerrttiilliizzaatteedd eegggg
 3 days after ovulation, the morula
(early blast)is fomulated
 4 days after ovulation, the late blast
is fomulated
 6-7 days after ovulation, the egg
imbeds in the uterus

5. TThhee ssttaaggee ooff eegggg iimmbbeedd
 Apposition
 Adhesion
 Penetration

6. TThhee nneecceessssaarryy ccoonnddiittiioonnss
ooff iimmbbeedd
 Disapearing of the pellucid zone
 Syntrophoblast formed from the
blast
 Synchronizing development of blast
and the endometriun
 P Secretory enough

7. CChhaannggeess ooff eennddoommeettrriiuumm aafftteerr
tthhee eegggg iimmbbeedd
The
endometrium
changes into
dicedua
 Basal decidua
 Capsular
decidua
 True decidua

8. AAttttaacchhmmeenntt ooff tthhee ffeettaall
 Placenta
 Fetal membranes
 Umbilical cord
 Amniotic fluid

9. ppllaacceennttaa
It’s an exchange organ between
maternal and fetal
 Amniotic membrane
 chorion frondosum
 Basal decidua

10. cchhoorriioonn ffrroonnddoossuumm
13-21 days after ovulation, villi
fomulating gradually
 Grade I viili
 Grade II Iviili
 Grade III viili

11. SSttrruuccttuurree ooff ppllaacceennttaa
 Round
 Weight:450-650g
 Diameter:16-20cm
 Thickness:1-3cm
thick in center and thin in margin

12. FFuunnccttiioonn ooff ppllaacceennttaa
One important function of placenta is
substance exchange between maternal
and fetal

13. The position of exchange is VSM(vasculo-syncytial
membrane)
VSM is comprised of
 Syntrophoblastocyte
 Basal membrane of Syntrophoblastocyte
 Stroma of villi
 Basal membrane of capillary
 Endothelium of capillary

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

15. The functions of placenta
 Gas exchange
 Suply of nutrition
 Depletion of fetal product of metabolisn
 Defense function
Hormone synthesis
Human chorionic gonadotropin(HCG)
Human placental lactogen(HPL)
Pregnancy specific b -glycoprotein(PS b 1G)
Human chorionic thyrotropin(HCT)
Estrogen, P, Oxytocinase, heat stable alkaline
phosphatase(HSAP)

16. Fetal membrane
 Chorion
 Amnion
Umbilical cord
 Length:30-70cm average:50cm
 Consist of 2 artery and 1 vein

17. Amniotic fluid
Source: early from serum dialysis
late fron fetal urine
Absorse: by fetal membrane, fetal
swallowing(500ml/day)
Amniotic exchange: between maternal
and fetal 400ml/h

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

19. Status of amniotic fluid
 pH:7.20
 Density:1.007-1.025
 Contained: water(98-99%)
inorganic substance
organic substance(1-2%)

20. The function of amniotic fluid
Protect maternal and fetal

21. Maternal changes during pregnancy
The maternal system may produce a
series of changes in order to adapt to the
needing of fetal growth and development
influenceed by placenta hormone and
neuro-endocrine

22. Changes of reproductive system
Uterus
Body: become enlargement and soft
from 7×5 ×3cm pre-pregnancy to
35×25 ×22cm at term
Volume of uterus cavity:
become enlargement from 5ml pre-pregnancy to
5000ml.at term

23. Weight: be increased from from 50g pre-pregnancy
to 1000g at term
Wall: become thickness and the thickist at mid-period
from 1 cm pre-pregnancy to 2-2.5
cm at term
Blood suply:blood flow increased significantly
upto 500- 700ml/min,increased 4-6
times and most of blood flow is
transported to the placenta(80-85%)

24. Isthmus: be dialated and become soft from 1cm
pre-pregnancy a portion of the uterus
after 12 gestational weeks
Cervix: be soft and coloration or stain
secrete amount of mucus avoiding the
uterus cavity suffer from infection

25. Changes of ovary
 Stop ovulation
 Corpus luteum formation and maintains for
10 weeks
 And the function of corpus luteum is
substituted by the placenta
 Corpus luteum atretic gradually after 3-4
months gestation.

26. Changes of the circulation
Heart border: become enlargement
Heart rate: increased 10-15 beat per min at the
late pregnancy
Heart volume: increased 10% at the late
pregnancy

27. Cardiac output
Very important for fetal growth and development
Incrased begain 10 weeks and upto the peak
at 32 weeks
80ml/bp and keeps the level to the term
pregancy

28. Blood pressure changes due to pregnancy
 No obvious change in Systolic pressure
 Mild decreased in diastolic pressure
Vein pressure
 No significantly changes in Upper limb vein
pressure
 Lower limb vein pressure increased because of
the disturbance of vein reflux

29. Changes of blood system
Volume: increased (30-45% ) begain 6- 8 weeks
and up to the peak at 32-34 weeks
increased about 1500ml including
plasma 1000ml and red cell 500ml

30. Changes of blood component
Red cell: reticulocyte increased
red cell decreased 3.6×1012(4.2×1012)
Hb decreased 110g/L(130g/L)
WBC: neutrophilic granulocyte increased
lymphocyte mild increased
no change in orther blood cells

31. Coagulation
Hypercoagulability
Factor ⅱⅴⅶ ⅷ Ⅸ ⅹ increased
ESR increased significantly upto 100mm/h
Plasma protein
albumin decreased