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Fertilization, Implantation and early
Development of the embryo
Lecture 3
3/10/2006

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 Remarkable organ originating from trophoblast layer of fertilized ovum.
Placental functions
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Transport
Respiratory
Nutrient function
Hormone production
Storage
Barrier function (molecular as heparin, syphilis, toxoplasma

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– Placenta Marginata : disorder of placental attachment, mild type of abruption in which slight separation occurs at the edge of placenta in region of marginal sinus of mother.
– Placenta circumvallata : opaque ring seen on fetal surface, its formed by doubling edge.
– Placenta membranacea : covered all of the fetus.
– Placenta Accretta, increta, percreta

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 Rate of growth development under control of genetic control and nutrient in body
 Size
--5th wk- sac
--12th wk-30gm
--28th wk-1100gm
--Full term-50cm (2700-3600 gm)

Fetal Circulation
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During intra uterine life of fetal, respiratory system is not functioning because oxygenation of blood is occurring in placenta, therefore 4-temporary structures in fetal circulation, these are
Ductus Venous : runs from umbilical vein to the vena cava, it carries oxygenated blood to the heart
Foramen Ovale : allows blood to flow from Rt atrium directly to Lf atrium (bypass Rt ventricle and fetal lungs).
Ductus Arterioses : communicating duct from pulmonary artery to descending arch of aorta, it carries deoxygenated blood.
Hypo gastric arteries : branching from internal iliac arteries to enter the umbilical cord as umbilical arteries

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Summary of fetal circulation
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O2 blood enters fetus via umbilical vein
Umbilical vein goes straight to liver ,however most of blood go to Ductus venous to inferior vena cava
Inferior vena cava carrying co2 blood from lower parts of fetus
Inferior vena cava empties its blood into Rt atrium
Main volume of blood passes straight to Lt atrium via foramen Ovale.
From Lf atrium blood passes to Lt ventricle and out into aorta to supply brain and upper limbs
Co2 blood returned from upper part of body via superior vena cava
From superior vena cava blood travels through Rt atrium and ventricle to enter pulmonary artery
Most of the blood bypasses through Ductus Arterioses straight to descending arch of aorta
Main volume of blood diverted through hypo gastric arteries to cord and then to placenta as umbilical arteries for replenishment.

Changes after birth
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 After clamping umbilical cord and take first deep breath as a result of stimuli like
Infant’s thorax first compressed and rapidly re expands during delivery
-Cold of external environment
-Bright lights
-Noises
Pressure on infant’s body and sensation of weight

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 Allows growth and free movement of fetus
 Equalizes pressure and protect fetus from injury
 Maintains temperature and provides small amounts of nutrients
 In labour protects placenta and umbilical cord from pressure of uterine contractions
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 Aids effacement of cervix and dilatation of uterine os.

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 Polyhydraminus: exceeds 1500 ml (e.g. encephalopathy)
 Oligohydraminus: less than 300 ml (e.g. fetus unable to pass urine)
 Meconium: in case of fetal distress

 Length 15-120 cm (average 50cm) sufficient to allow delivery of baby without traction to placenta occur.
 -Transmits umbilical blood vessels
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 -Two arteries from internal iliac artery, un oxygenated blood and one vein from Ductus venosus having oxygenated blood.

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 Less than 40 cm short cord
 Very long cord may wrapped around neck or body of fetus or become knotted
 True knots result occlusion of blood vessels
 False knots

Fetal Membranes (amniotic Sac)
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 Function
 keep amniotic fluid
 Asses in formation of fluid
 Protection
 Asses material exchange.

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Terminology
 Para - number of births after 20 weeks gestation regardless of whether the infants were born alive or dead, twins are considered a single para
 Primagravida - woman pregnant for the first time
 Mulrigravida - woman who is in her second or more pregnancy

Terminology
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 Gravida -any pregnancy, regardless of duration
 Nulligravida - a woman who has never been pregnant
 Primapara -woman who has not given birth at more than 20weeks gestation
 Multipara -woman who has given birth two or more times at more than 20 weeks gestation

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 Average Pregnancy lasts 280 days40 weeks and is divided into trimesters
– 1 st trimester 0-
3months(13WK)
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2 nd Trimester 3-6 months(26WK)
3 rd Trimester-6-9 months(39WK)
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10 lunar months
9 calendar months

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Profile of previous obstetric history
 GTPALM
 G =gravida
 T =term
 P =premature births
 A =abortions
 L = number of living children
 M = multiple births

 A lady who is pregnant has 3 children and a history of 1 miscarriage (abortion).
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 This would be written as follows
– G T P A l M
– 5-3-0-1-3-0

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– P & G to indicate PARA and Gravida
– A woman pregnant for the first time would be
 P 0, G 1
 A woman is pregnant has 4 children and has a history of 2 abortions
 P4, G 7

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DETERMINATION OF DATE OF
BIRTH
 Nagele ’s rule
 1st day LMP - 3 months + seven days
 LMP Oct 10 th2003
 -3mts July 10 th
 +7 days
 EDD= July 17 th 2004

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Improved pre-natal care has dramatically reduced infant and maternal mortality
Detecting potential problems early leads to prompt assessment and treatment
Preventative measures such as adequate nutrition, proper exercise, assessment of pregnancy and a planned regimen of care are essential
A pregnant woman should seek health care as soon as she suspects she is pregnant

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The initial pre-natal visit
 The initial visit will include the following data collection
– Health history
– Past medical history
– Genetic disorders
– Obstetric history
– Personal & social history
– Physical assessment

 last period started on
 menstrual cycles are regular and how long they usually last;
 details about any gynecological problems
 details about any previous pregnancies.
 medical history, including chronic conditions and medications used to treat them, drug allergies, psychiatric problems, and any past surgeries or hospitalizations
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 ask about activities such as smoking, drinking, and drug use that could affect pregnancy.

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 ask if you, the baby's father, or anyone else in the family has a chromosomal or genetic disorder or was born with a structural birth defect.
 know about all the medications and nutritional supplements you've taken since your last period
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 any exposures to potential toxins

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 At each pre-natal visit the nurse collects the following data
– Weight
– Urine for glucose & protein
– Vital signs
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Doppler of the fetal heart beat
Leopold ’s maneuvers to determine presentation of the fetus
– Assessment of fundal height

(table9.2),P.223
– Presumptive signs -these signs suggest pregnancy
– Probable signs -indicate that the woman is most likely pregnant
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– Positive signs definite evidence that a woman is pregnant

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Presumptive
Amenorrhea
Nausea & vomiting
Urinary frequency
Quickening
Uterine enlargement
Pigmentation changes
Probable
Goodell’s
Hegar’s
Chadwick's sign, ballottement braxton hicks contractions
+preg test
Positive
Fetal heart sounds,
Outline & move on ultrasound

How do pregnancy tests work?
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 All pregnancy tests look for a special hormone in the urine or blood that is only present when a woman is pregnant. This hormone, human chorionic gonadotropin
(hCG), is also called the pregnancy hormone.

What's the difference between a urine and a blood pregnancy test?
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 Blood tests can pick up hCG earlier in a pregnancy than urine tests can.
-Blood tests can tell if you are pregnant about 6 to
8 days after you ovulate (or release an egg from an ovary ).
-Urine tests can determine pregnancy about 2 weeks after ovulation. Some more sensitive urine tests can tell if you are pregnant as one day after you miss a menstrual period.

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 eat well
 weight gain
 Discomfort of early pregnancy
 symptoms that require immediate attention

 Health-seeking behaviors related to interest in maintaining optimal health during pregnancy
 Anxiety related to minor symptoms of pregnancy
 Risk for fluid volume deficient related to nausea and vomiting
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 Constipation related to reduced peristalsis during pregnancy

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 Disturbed body image R/T change of appearance with pregnancy
 Risk for ineffective sexuality patterns
R/t fear of harming fetus during pregnancy.
 Disturbed sleep pattern R/t frequent need to empty bladder during night
 Fatigue R/t metabolic changes of pregnancy.

 Headache –visual disturbances, or dizziness
 Increase in systolic BP 30mmHg or more
 Increase in diastolic blood pressure 15mmHg
 Epigastric pain
 Burning on urination or backache
 Abnormal fatigue and nervousness
 Anginal pain, shortness of breath
 Muscular irritability, confusion, seizures
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 Vaginal bleeding or fluid leaking from the vagina