Transcript Trimester One

Trimester One
Corbyn, Whitney, Ashley, Brittany
Week One & Two
-not actually pregnant the first week or two
- sperm and egg unite in one of your fallopian
tubes to form a zygote
-zygote has 46 chromosomes - 23 from oocyte
and 23 from sperm
-amnion sac is formed
Week 3
-Nervous system begins to develop
-heart beating starts
-At this point the baby is smaller then a pen point
Week Two
Week Three
 -Nervous system begins to
develop
-heart beating starts
-At this point the baby is
smaller then a pen point
Week Four
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Although you are as yet
unaware that you are pregnant,
your baby is already
undergoing great changes.
The fertilized egg is now a
quickly growing ball of cells
called a blastocyst.
It is embedded more deeply in
the uterine wall and the
amniotic cavity is being
formed.
The group of cells that will
make up the placenta is being
organized and circulatory
networks containing maternal
blood are being formed.
Three layers of cells are sorting
themselves out within the
blastocyst.
The ectoderm will form the
nervous system, hair and skin of
your baby. The endoderm will
become the lining of the
gastrointestinal tract, and various
organs like the thyroid, liver and
pancreas.
The mesoderm will develop into
the skeleton, connective tissues,
blood systems, urogenital system
and most of the muscles
Week Five
Your baby is now an embryo (socalled due to the little tail at the
end of its developing spine) and is
only barely visible to the naked
eye.
The spinal column, brain and
heart have begun to develop.
Baby is about 1/16th of an inch
long
Week Six
 The baby's heart has begun to beat! At
about ½ inch long your little one is the size
of your little fingernail.
 He has begun to grow buds where his arms
and legs will be and his head has the
beginnings of eyes, ears and a mouth.
Starting prenatal care now is essential. For
the next four weeks your baby will be most
vulnerable to factors that can interfere with
proper development.
 Now is the time, if you haven't already, to
stop smoking, drinking or indulging in
recreational drugs. Also, be particularly
sensitive to environmental risks such as
exposure to chemicals, tobacco smoke and
animal diseases; some of which,
toxoplasmosis for instance, can be
contracted by humans
Week Seven
 The baby's heart is now beating
regularly at 150 beats per minute.
 The arm buds have grown and now
the hands are beginning to
develop.
 The whole baby is still only 1/3 of
an inch long, but the brain,
intestines, pituitary gland and
pancreas are growing.
 Though the genital tubercle is
present, you can't tell by looking
whether it is a girl or a boy, yet.
 The baby's face is developing
rapidly, the nasal pits have formed,
the ears are developing and there
are developing lenses on the eyes.
Week Eight
 Your baby is now about 10,000
times bigger that it was at
conception but is still only about
an inch long.
 This week the baby's gonads will
either become testes or ovaries.
The eyes are formed and
covered by a fold of skin, though
the eyelid will not open yet.
 The arms and legs are growing
longer and the arms are bent at
the elbow, allowing the baby to
hug herself. The tip of the nose
is now visible and teeth are
forming under the baby's gums.
 Your little one is beginning to
move around now and kick his
legs, but he is still way too small
for you to feel it.
Week Nine
 The baby officially changes
from being an embryo to a
fetus this week. This is mostly
due to the fact that his little
embryonic tail has
disappeared.
 Bones and cartilage are
beginning to form.
 The umbilical cord and
placenta are forming and
growing.
 If touched from the outside of
the uterus, the baby will
respond by moving. The
fingers have formed but are
webbed.
Fact: at the end of this week the babies arms are the length of this printed 1
Week Ten
• Most of the baby's joints are formed
now-shoulders, elbows, wrist, hands
and fingers, knees, ankles, feet and
toes. All of his organs are present and
accounted for, but not fully formed or
functional. Your little one is now about
as long as a paper clip and weighs
the same as four paperclips, in other
words: 1 ¾ inch and ¼ oz.
Week Eleven
 Your baby's little
fingers are growing
nails now. The baby
probably will double
his length this week.
The irises of your
baby's eyes are
developing now.
Week Twelve
 The baby's chest is rising
and falling as it practices
breathing movements..
 With kidneys that are
fully functioning the baby
can swallow amniotic fluid
and excrete it as urine.
 The amniotic fluid is
completely replaced every
3 hours, so the baby's
environment stays fresh.
Even though she is not
eating yet, the baby's
intestines are contracting
in peristaltic movements
as if she were digesting
food
Teratogen
~Thalidomide
-This drug was used to
control nausea
during pregnancy
-Thalidomide was used
in the late fifties and
removed from the
market in 1961
-Thalidomide causes
deformities in the
developing fetus.
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Deformities such as
defective intestines,
hearing defects or no
ears at all, and
impaired vision.
-Many of the foetuses
were born with
undeveloped limbs or
no limbs at all.
~Radiation
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There are a number of ways to be
exposed to radiation: having a
medical X-ray, working at a
nuclear power plant, working in
any industrial setting where X-rays
or with other radioactive
substances. Countless other minor
sources such as TVs, smoke
detectors, and airplane trips.
Radiation exposure at high
enough levels can cause
developmental risks to a
developing fetus like a reduction
in height, severe mental
retardation, small head size,
impaired brain development,
childhood leukemia, and cancer in
later life.