Physiology of pregnancy Zhao aimin

Definition of pregnancy 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

Definition of fertilazation 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)

The Development of the fertilizated egg  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

The stage of egg imbed  Apposition  Adhesion  Penetration

The necessary conditions of imbed  Disapearing of the pellucid zone  Syntrophoblast formed from the blast  Synchronizing development of blast and the endometriun  P Secretory enough

Changes of endometrium after the egg imbed The endometrium changes into dicedua  Basal decidua  Capsular decidua  True decidua

Attachment of the fetal  Placenta  Fetal membranes  Umbilical cord  Amniotic fluid

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

chorion frondosum days after ovulation, villi fomulating gradually  Grade I viili  Grade II Iviili

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

Function of placenta One important function of placenta is substance exchange between maternal and fetal

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

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

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  -glycoprotein(PS  1G)  Human chorionic thyrotropin(HCT)  Estrogen, P, Oxytocinase, heat stable alkaline phosphatase(HSAP)

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

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

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

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

The function of amniotic fluid Protect maternal and fetal

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

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

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 cm at term Blood suply: blood flow increased significantly upto ml/min,increased 4-6 times and most of blood flow is transported to the placenta(80-85%)

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

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.

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

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

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

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

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

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