A Healthy Pregnancy
Unit Two
Prenatal Development
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Objectives:
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To name the three stages of
Pregnancy
Describe the prenatal
development during each of
the three stages of Pregnancy
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Prenatal Development
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1.
2.
3.
Prenatal development is the development of
the baby during the period before birth.
Prenatal development is considered in three
stages:
Period of the Zygote
Period of the Embryo
Period of the Fetus
3
Period of the Zygote
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Conception
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Conception occurs with the union of the Ovum (a
female cell or egg) and the Sperm (male cell).
This union is called the Zygote or fertilized egg
This stage begins at conception and lasts until the
zygote is implanted in the mother’s uterus.
The period of the Zygote lasts approximately two
weeks (10-14 days)
The zygote grows to be about the size of a pinhead.
Roots grow from the zygote into the wall of the uterus
where they can receive nutrients from the mother’s
blood.
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Conception
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Embryo
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The 2nd stage of pregnancy is he period of the embryo
The embryo is the developing cluster of cells in the uterus
& lasts from about 2 weeks to 8 weeks after conception
The embryo is attached to the mother by the umbilical
cord (20 inches long) which reaches from the embryo’s
stomach to the wall of the uterus.
The umbilical cord contains arteries which carry the
embryo’s waste products away from the embryo to the
mother’s blood system to be purified. It also brings
oxygenated and nutrient-rich blood back to the embryo to
keep it alive.
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Period of the Embryo
First Month
•By the end of the
first month, the
embryo is about 1/10
of an inch long. The
heart, which is no
larger than a poppy
seed, has begun
beating.
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Period of the Embryo
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The umbilical cord is connected to the placenta.
The placenta is an organ which serves as a medium for
the exchange of nutrients and waste between the
mother and the fetus.
Throughout this period, the embryo is inside the
amniotic sac (a bag filled with watery substance called
amniotic fluid). The fluid will protect the developing
baby against bumps, bruises and temperature changes.
During this period all of the organs that will be present
at birth are formed.
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Embryo -Two Months
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The embryo is about
1 inch long and has
distinct, slightly
webbed fingers.
Veins are clearly
visible. The heart has
divided into right and
left chambers.
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Fetus
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The third development period is called the period of
the fetus.
This period extends from the end of the second month
of pregnancy until birth. During this stage, the
developing baby is referred to as a fetus.
The body parts, organs and systems which were formed
during the embryo period will become much more
developed and begin to function.
The fetus will begin will begin to resemble a human
being and features will increase in clarity.
During the fetal period the baby may increase in length
as much as twelve inches.
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Three Month Fetus
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By now the fetus is 2
1/2 to 3 inches long
and is fully formed.
He has begun
swallowing and
kicking.
All organs and
muscles have formed
and are beginning to
function.
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Quickening
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The sensation of feeling life called quickening,
tells the mother that she does have a live within
her child
This happens sometimes between the fourth or
fifth months
These fluttering movements are faint or
infrequent a first but gradually become sronger
and more frequent.
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Fetus - Fourth Month
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Your baby is covered
with a layer of thick,
downy hair called
lanugo.
His heartbeat can be
heard clearly. This is
when you may feel
your baby's first kick
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Fetus-
th
4
Month
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Fetus Five Months
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A protective coating
called vernix
caseosa begins to
form on baby's skin.
By the end of this
month, your baby will
be nearly 8 inches
long and weigh
almost a pound
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Fetus Six Months
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Eyebrows and
eyelids are visible.
Your baby's lungs are
filled with amniotic
fluid, and he has
started breathing
motions.
If you talk or sing, he
can hear you.
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Six Month Fetus
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Fetus Seven Months
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By the end of the
seventh month, your
baby weighs about 3
1/2 pounds and is
about 12 inches long.
His body is well-formed.
Fingernails cover his
fingertips
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Fetus Eight Months
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Your baby is gaining
about half a pound
per week, and layers
of fat are piling on.
He has probably
turned head-down in
preparation for birth.
He weighs between 4
and 6 pounds.
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8th Month Fetus
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Fetus Nine Months
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Your baby is a hefty 6
to 9 pounds and
measures between 19
and 22 inches.
As he becomes more
crowded, you may
feel him move around
less.
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Lightening
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Sometimes during the ninth month, the beby’s
weight seems to shift down and the mother feels
more comfortable in her upper abdomen.
This is called Lightening
This means the baby has dropped into he birth
canal and birth is not far off
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Weight Gain
The recommended
weight gain for the
average woman
during pregnancy is
25-30 pounds and is
distributed as
follows:
Baby
7.5 lb
Placenta
1.5 lb
Uterus
Amniotic
Fluid
Extra Blood &
Water
Retention
Breast Tissue
Maternal
Stores of
Protein
2 lb
1.5 lb
4.5 lb
3 lb
4 lb
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