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Wang Fu-ling
Chapter3 Normal pregnancyChapter3 Normal pregnancy
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Pregnancy physiology
Pregnancy is the maternal condition of
having a developing fetus( ) in the
body.
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What is pregnancy?What is pregnancy?
Pregnancy is defined as the course of
embryo and fetal growth
and development in uterine
It begain at the fertilization and end thedelivery of the fetal and its attachment
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The fetusThe fetus
1 Fetus growth and development
2 Fetal physiology
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11 Fetus growth and developmentFetus growth and development
Fertilization is defined as the course of
combination of the oocyte and sperm
It onset12h after ovulation usually in
ampulla of the oviduct(fallopian tube)
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11 Fetus growth and developmentFetus growth and development
The human conceptus from fertilization
through the eighth week of pregnancy is
termed an embryo from the eighth weekuntil delivery it is a fetus.
The estimated age of the fetus calculated
from the frist day of the last menstrualperiod ,assuming a 28-day cycle.
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11 Fetus growth and developmentFetus growth and development
During the frist 8 weeks,the term embryo is
used to denote( ) the developing
organism because it is during this time thatall the major organs are formed .
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11 Fetus growth and developmentFetus growth and development
After the eighth week, the word fetus is
proper, the growth of the fetus may be
described in units of 4 weeks gestationalage, beginning with the first day of the
LMP
last menstrual period
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11 Fetus growth and developmentFetus growth and development
8weeks: the organs are beginning to form
12weeks: the fingers and toes have nails,and the
external genitalia may be recognizable 16weeks :the sex is discernible as male or female
20weeks :heart tones may often be detected by
stethoscope(
),movements have beenperceives by mother,the uterine fundus is near the
level of the umbilicus
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11 Fetus growth and developmentFetus growth and development
24weeks some fat is beginning to be deposited
beneath the wrinkled skin,viability is reached by
the 24th week,but survival at this stage is stillrelatively rare
28weeks the lungs are now capable of
breathing,but the surfactant content is low;survival
is possible in level II or level III neonatal centers
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11 Fetus growth and developmentFetus growth and development
32weeks if born at this stsge,about 5 of 6
infants survivie
36weeks the skin has lost its wrinkledappearance,the chances for survival are good
40weeks the head has a maximal transverse
diameter of 9.5cm. The average fetus
,therefore,requires cervical dilatation of almost
10cm before it can descend into the vagina
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22 Fetal physiologyFetal physiology
Contents:
Circulatory function
Hematology( )
Respiratory function
Gastrointestinal functionRenal function
Endocrinology( )
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22 Fetal physiologyFetal physiology
1 Circulatory function
2) fetus placenta mother
3) Umbilical cord: 1 umbilical vein (full of
oxygen), 2 umbilical artery (lack of
oxygen)
4) Mixed blood (vein and artery)
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Development of embryo and fetusDevelopment of embryo and fetus
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22 Fetal physiologyFetal physiology
2 HematologyErythropoiesis
From yolk sac : 3 weeks
From liver: 10 weeks
From bone marrow and spleen after 10 weeks
*By10weeks the liver assumes the major role inerythropoiesis,but the spleen and bone marrowgradually take over this function
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22 Fetal physiologyFetal physiology
(3) Respiratory function
gas exchange in the fetus occurs in the
placenta
(4) Gastrointestinal tract
No truly function until after birth
(5) Kidney
Its function begins at 9-12th week
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22 Fetal physiologyFetal physiology
(6)Endocrinology Fetal thyroid: the first endocrine gland (6th
week), synthesize thyroxine at 12th
week
Fetal adrenal cortex consists mainly of a fetalzone that disappears about 6months after birth.
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33 The placentaThe placenta umbilical cordumbilical cord
and amniotic fluidand amniotic fluidThe placenta
The umbilical cord
The amniotic fluid
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11 The placentaThe placenta
Development of the placenta
Functions of the maternal placental-fetal
unit
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11 The placentaThe placenta
Structure
2. Primary villus
3. Secondary villus
4. third class villus
fetal capillary(
) enter thestroma
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*1 Development of the placenta
Fertilization
3. Place: oviduct (ampulla)
4. Process
capacitation acrosome reactionpenetrate the zona pellucida second
meiosis zygote( )
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Implantation
2. requirement
Disappear of zonapellucida
Formation ofsyncytiotrophoblast
Synchronized development of blastocystand endometrium
Adequate progesterone
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1. Process
morula (day 3) enter uterine cavity
(day 4) early blastocyst lateblastocyst (day 6-7) implantation
location adherence penetration
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22 Functions of the maternalFunctions of the maternal
placental-fetal unitplacental-fetal unit
Endocrine function
Human chorionic
gonadotropin HCG
Human chorionic somatomammotropin
Placental proteins
Estrogen
Metabolitic function
Protective function
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Endocrine functionEndocrine function
Human chorionic gonadotropin(HCG) It is a glycoprotein that has biologic and
immunologic similarities to luteinizing hormonefrom the pituitary
H CG is produced by the syncytiotrophoblast ofthe placenta
This measurement is useful because it can detectpregnancy in all patients on day 11 afterfertilization
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Endocrine functionEndocrine function
Human chorionic somatomammotropin(hGS)
hGS is a protein hormone with
immunologic and biologic similarities topituitary growth hormone
It has been suggested that hGS is the
growth hormoneof pregnancy
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Endocrine functionEndocrine function
Placental proteins
PAPP-A,PAPP-B,PAPP-C,PAPP-D
PAPP-D is the hormone hCS
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Endocrine functionEndocrine function
Estrogen
Estrogen production by the placenta is
dependent upon precursors reaching it fromboth the fetal and maternal compartments
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Metabolitic functionMetabolitic function
The primary function of the placenta is the
transport of oxygen and nutrients to the fetus and
the reverse transfer of CO2(carbon dioxide), urea,and other catabolites back to the mother.
These compounds are required for the synthsis of
new tissues,eg,amino acids vitamins and so on.
Substances such as certain maternal hormones,
which may modify fetal growth.
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Protective functionProtective function
The placental membranes are often referred
to as a barrier to fetal transfer, but there
are few substances(eg, drugs) that will notcross the membranes at all.
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22 The umbilical cordThe umbilical cord
In the early stages, the embryo has a thick
embryonic stalk containing 2 umbilical
arteries,one large umbilical vein,the allantois ,and primary mesoderm( ).
At birth the mature cord : long 50-60cm
diameter 12mm
A long cord is defined as more than 100cm and a
short cord as less than 30cm.
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33 The amniotic fluidThe amniotic fluid
In the first of pregnancy,amniotic fluid
volume appears to increase in association
with growth of the fetusAverage volume 800ml
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Amniotic fluidSource: early from serum dialysis( )late from fetal urine
Absorb: by fetal membrane, fetal
swallowing(400-500ml/day)
Umbilical cord
Fetal skin
Amniotic exchange: between maternaland fetal 400ml/h
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Volume of amniotic fluid
8 weeks:5-10ml
10 weeks:30ml
20 weeks:400ml
38 weeks:1000ml
Note: After 38weeks, both amniotic fluid
and maternal plasma volume decrease.
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Status of amniotic fluid
pH:7.20
Density:1.007-1.025
Contained: water(98-99%)
inorganic substance( )
organic substance(1-2%)
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The functions of amniotic fluidThe functions of amniotic fluid
Cushions the fetus against severe injury
Provides a medium in which the fetus can moveeasily
Warm
May be a source of fetal nutrients
In early pregnancy,is essential for fetal lung
development Protect mother
Prevent infection
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44 Maternal physiology duringMaternal physiology during
pregnancypregnancyThe physiologic,biochemical,and anatomic
changes that occur during pregnancy are
extensive and may be systemic or local.Those maternal adaptation maintain a
healthy environment for the fetus.
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Content:Content:
Genital tract
Breasts
Cardiovascular system
Hematologic system
Pulmonary system
Gastrointestinal tract
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11 Genital tractGenital tract
Uterus
OvariesVagina and perineum
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Changes of uterus
Body: become enlargement and soft
from 75 3cm pre-pregnancy to
3525 22cm at term
Volume of uterus cavity:
become enlargement from 5mlpre-pregnancy to
5000ml.at term
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Weight:be increased from 50g pre-
pregnancy to 1100gat term
Blood supply:blood flow increased significantly
up to 450-650ml/min,increased 4-6
times and most of blood flow istransported to the placenta(80-85%)
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Isthmus:be prolonged 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
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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.
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Vagina and perineumVagina and perineum
During pregnancy,increased vascularity and
hyperemia develop in the skin and muscles
of the perineum and vulva,and there issoftening of the normally aboundant
connective tissue( ) of these
structure.
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22 BreastsBreasts
In the early weeks,the pregnant woman often
experiences tenderness and tingling.
After the second month,the breasts increase in sizeand delicate veins become visible just beneath the
skin.
After the first few months,a thick,yellowish
fluid,colostrum,can often by expressed from thenipples by gentle massage( )
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33 Cardiovascular systemCardiovascular system
Heart
Cardiac output
Blood pressure
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Heart
Heart border:become enlargement
Heart rate:increased10-15 beat per min at the
late pregnancy
Heart volume: increased10% at the late
pregnancy
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Cardiac outputVery important for fetal growth and development
Increased begin 10 weeks and upto the peak
at32-34 weeks and continuing at this level
until term
Cardiac output increase approximately 40%
during pregnancy
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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
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44 Hematologic systemHematologic system
Blood volume
Blood components
Red blood cells
White blood cells
Clotting factors
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Changes of blood systemVolume: the average increase in volume at
term is 45-50%. Hypervolemia begins in the frist
trimester,increses rapidly in the second
trimester,and the peakat about the 30th week.
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Changes of blood components
Red cell:the increase in red blood cell mass is about
33%,or approximately 450ml of erythrocytes(
).Since plasma volume increases earlier in pregnancy
and faster than red blood cell volume,after the end of
second trimester( 3 ) :
red cell decreased 3.61012(4.21012)
Hb hemoglobin decreased
110g/L(130g/L)
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WBC(white blood cell):the total blood
leukocyte count increases during normal
pregnancy from a pregnancy level of4300-4500/uL to 5000-12000/uL in the
last trimester.
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Clotting factors:
Duringpregnancy , level of several essential
coagulation factors increase.There are markedincreases in factorI VII VIII IX Xand
XII .
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(5)(5) Pulmonary systemPulmonary system
Pregnacy produces anatomic and
physiologic changes that affect respiratory
performanceTotal lung capacity is reduced(4-5%)by the
elevation of the diaphragm
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(6)(6) Gastrointestinal tractGastrointestinal tract
During pregnancy,nutritional requirements
are increased,and several maternal
alterations occur to meet this demand
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Diagnosis of pregnancyDiagnosis of pregnancy
The diagnosis of pregnancy is usually made
on the basis of a history amenorrhea
,an enlarging uterus,and a positivepregnancy test
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11 Diagnosis of the first-trimesterDiagnosis of the first-trimester
pregnancypregnancy History and symptoms
Signs
Assistant examination
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11 History and symptomsHistory and symptoms
Amenorrhea
It is a fairly reliable sign of conception in
women with regular menstrual cycles.In women with irregular cycles,it is not a
reliable sign. Delayed menses may also becaused by other factors such as emotionaltension,chronic disease,endocrinedisorders,and so on.
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Morning sickness nausea andvomiting :
This common symptom occurs in approximately50% of pregnancies.
It begins at about 6 weeks gestation and disappearsat about 12 weeks gestation in most patients.
It is usually most severe in the morning but canoccur at any time.
The cause is probably rising serum levels of HCG.
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Bladder frequency :It occurs because of increased bladder circulation
and pressure from the enlarging uterus.
It usually disappears after 12 weeks gestation when
the uterus enlarges so much that its no longer a
pelvic organ.
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(2)Signs(2)Signs
Changes in the genital organs
Changes in breasts
A. Mastodynia( )
B. Enlargement
C. Linea nigra
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(3) Assistant examination(3) Assistant examination
Pregnancy test : urine testing
Ultrasound examination
Increased basal body temperature
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Pregnancy test
Sensitive early pregnancy tests measure
changes in levels of HCG.If maternal renal function is normal, urine
values are usually proportionate to serumvalues.
Radioimmunoassay for HCG is a sensitiveand specific test for early pregnancy.
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Increased basal body temperature
Persistent elevation of basal body
temperature over a 3-week period usuallyindicates pregnancy if temperatures have
been carefully charted.
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22 Diagnosis of the second andDiagnosis of the second and
third-trimester pregnancythird-trimester pregnancy
Symptoms and signsAssistant examination
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(1)Symptoms and signs(1)Symptoms and signs
Uterine enlargement
Quickening( )
Fetal heart tones
Palpation( ) of fetus
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Uterine enlargementAt 16 weeks, the uterus is usually at the midpoint
between the pubic and the umbilicus.At 20 weeks ,the uterus is palpable at the
umbilicus.
At 26-34 weeks, fundal height correlates roughly
with the estimated gestational age.But after 36 weeks, the fundal height may
decrease as the fetal head descends into the pelvis.
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Quickening( )The first fetal movement is usually
appreciated at 17 weeks in the averagemultipara and at 18 weeks in
the average primipara( ).
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Fetal heart tones
It may be heard at 20weeks.
The normal fetal heart rate is 120-160beats
per minute.
It is best to palpate the maternal pulse for
comparison.
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Palpation( ) of fetusAfter 20 weeks, the fetal outline can be
palpated through the maternal abdominalwall.
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(2)Assistant examination(2)Assistant examination
Ultrasound examination----ultrasound is
used to measure fetal growth parameters, to
estimate fetal weight, to access fetalanatomy, and to measure amniotic fluid
volume.
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33 Pregnancy monitoringPregnancy monitoring
The perinatal interval is the span of fetaland neonatal life.
The perinatal interval of life may be dividedinto 2 periods:
Perinatal period I :28weeks of completedgestation to the frist 7days of life
Perinatal period II: 20weeks of gestationthrough 27days of life
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Prenatal care(Prenatal care(
))The purpose of prenatal care is to ensure,as
much as possible, an uncomplicated
pregnancy and the delivery of a live healthyinfant.
Mothers and offspring who receive prenatal
care have a lower risk of complications.
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44 Initial office visit(Initial office visit( ))
1 History
2 Physical examination
3 Laboratory tests
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11 HistoryHistory
Present pregnancy The interview should beginwith a full discussion of the symptoms; todetermine the duration of pregnancy, the patient
with regular menses may be able to accuratelycalculate the estimated date of confinement(EDC),using the first day of the LMP(LMP-3months+7days)
Previous pregnancy :eg: events of priorpregnancies provide inportant clues to potentialproblems in the current one.
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Medical history:eg: a history of
cardiovascular gastrointestinal , and
endocrine disorders.Surgical history eg a history of
previous gynecologic surgery
Family history : eg history of diabetesmellitus
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(2)Physical examination(2)Physical examination
General examination( )
Pelvic examination
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General examination(General examination( ))
A complete physical examination must be
performed on every new patient.
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Pelvic examinationPelvic examination
Pelvic soft tissue any pelvic mass should
be described accurately and evaluated by
Ultasound examination.Bony pelvis : pelvic
inlet midpelvis pelvic outlet
Cervical length: average cervical length is3-4cm
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Laboratory testsLaboratory tests
The following laboratory assessments shouldbe performed as early as possible inpregnancg and some of these repeated atleast once between 24 and 36 weeksgestation:
Blood screening
Genetics testingUrine testing
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55 Subsequent visitsSubsequent visits
The standard schedule for prenatal officevisits is:
0-32week:once every 4weeks;32-36weeks:once 2weeks;
36weeks to delivery:once each week
Weight, gain blood pressure, fundal height,findings on abdominal examination byLeopolds maneuvers
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66 nutrition in pregnancynutrition in pregnancy
The pregnant woman should be encouraged
to eat a balanced diet and should be made
aware of special needs for iron, folic acid,and zinc.
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