Download Child Studies 11 Fetal Development PP

FETAL
DEVELOPMENT
Courtesy of:
Peggy Pannell RN, MSN
FERTILIZATION
• Begins with 46 pair of chromosomes,
splits off to 23 then combine for a unique
new 46 pair.
Stages and Time Frames
Blastocyst
Germinal
Stage
Embryo
Embryonic
Stage
Fetus
Fetal Stage
Ovum
Before
fertilization
Blastocyst
0-2 weeks
Embryo
2-8 weeks
Fetus
8-40 weeks
IMPLANTATION
First weeks of human
development:
Blastocyst - early development of
the embryo from ovulation
through implantation in humans.
(Days 5-9). Embeds in
endometrium.
Implantation occurs after the
fertilized egg gets to the uterus
and attaches to the lining of the
uterus, or endometrium. The cells
keep dividing.
GESTATIONAL AGE
• Gestational age (duration of pregnancy)
equals time since LNMP (LNMP=Last
Normal Menstrual Period)
• Since Fertilization
Days
Weeks
Calendar Months
LNMP
280
40
9
Lunar Months
10
TRIMESTERS
Trimester
1st = weeks 1-13
2nd = weeks 14 - 26
3rd = weeks 27 and on
(38-40 WEEKS)
STAGES OF DEVELOPMENT
1 Month
• Baby Center Video:
Weeks 1-9
• First Trimester
At the end of four weeks:
• Baby is 1/4 inch in length
• Heart, digestive system,
backbone and spinal cord
begin to form
• Placenta (sometimes called
"afterbirth") begins to
develop
• The single fertilized egg is
now 10,000 times larger
than size at conception
Month 2
• First Trimester
At the end of 8 weeks:
• Baby is 1-1/8 inches long
• Heart is functioning
• Eyes, nose, lips, tongue,
ears and teeth are forming
• Penis begins to appear in
boys
• Baby is moving, although
the mother can not yet feel
movement
Month 3
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Baby Center Video: Weeks 1014
First Trimester
At the end of 12 weeks:
Baby is 2 1/2 to 3 inches long
Weight is about 1/2 to 1 ounce
Baby develops recognizable form.
Nails start to develop and
earlobes are formed
Arms, hands, fingers, legs, feet
and toes are fully formed
Eyes are almost fully developed
Baby has developed most of
his/her organs and tissues
Baby's heart rate can be heard at
10 weeks with a special
instrument called a Doppler
Month 4
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Baby Center Video: Weeks 15-20
Second Trimester
At the end of 4 months:
Baby is 6 1/2 to 7 inches long
Weight is about 6 to 7 ounces
Baby is developing reflexes, such as
sucking and swallowing and may begin
sucking his/her thumb
Tooth buds are developing
Sweat glands are forming on palms
and soles
Fingers and toes are well defined
Sex is identifiable
Skin is bright pink, transparent and
covered with soft, downy hair
Although recognizably human in
appearance, the baby would not be
able to survive outside the mother's
body
Month 5
• Baby Center Video: Weeks
21-27
• Second Trimester
At the end of 5 months:
• Baby is 8 to 10 inches long
• Weight is about 1 pound
• Hair begins to grow on baby's
head
• Soft woolly hair called lanugo
will cover its body. Some may
remain until a week after
birth, when it is shed.
• Mother begins to feel fetal
movement
• Internal organs are maturing
• Eyebrows, eyelids and
eyelashes appear
Month 6
• Second Trimester
At the end of 6 months:
• Baby is 11 to 14 inches
long
• Weight is about 1 3/4 to 2
pounds
• Eyelids begin to part and
eyes open sometimes for
short periods of time
• Skin is covered with
protective coating called
vernix
• Baby is able to hiccup
Month 7
• Third Trimester
At the end of 7 months:
• Baby is 14 to 16 inches long
• Weight is about 2 1/2 to 3
1/2 pounds
• Taste buds have developed
• Fat layers are forming
• Organs are maturing
• Skin is still wrinkled and red
• If born at this time, baby will
be considered a premature
baby and require special care
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Month 8
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Third Trimester
At the end of 8 months:
Baby is 16 1/2 to 18 inches long
Weight is about 4 to 6 pounds
Overall growth is rapid this month
Tremendous brain growth occurs
at this time
Most body organs are now
developed with the exception of
the lungs
Movements or "kicks" are strong
enough to be visible from the
outside
Kidneys are mature
Skin is less wrinkled
Fingernails now extend beyond
fingertips
Month 9
Third Trimester
At the end of 9 months:
• Baby is 19 to 20 inches
long
• Weight is about 7 to 7 1/2
pounds
• The lungs are mature
• Baby is now fully
developed and can survive
outside the mother's body
• Skin is pink and smooth
• Baby settles down lower in
the abdomen in
preparation for birth and
may seem less active
AMNIOTIC FLUID
• Protects Fetus
• Controls Temperature
• Allows Movement
• Source of oral fluid
• Clear, yellowish fluid surrounding the
developing fetus.
• Average amount 1000 ml.
UMBILICAL CORD
Connecting link between fetus and
placenta.
• Transports oxygen and nutrients to
fetus from the placenta and returns
waste products from the fetus to the
placenta.
PLACENTA
PLACENTA
mom
Baby
MOM
Baby
Schematic drawing of placenta: how it supplies oxygen and nutrition to embryo and removes waste
products. Deoxygenated blood leaves fetus through the umbilical arteries and enters placenta,
where it is oxygenated. Oxygenated blood leaves placenta through the umbilical vein, which enters
PLACENTA
Produces protein hormones:
• Human chorionic gonadotrophin
(HCG)- 8-10 days past conception, is
basis for pregnancy test
• Progesterone
• Estrogen
• Human Placental Lactogen
VIABILITY
• Capability of fetus
to survive outside
uterus at the
earliest gestational
age - 22-24 weeks
• Survival depends
on:
– Maturity of fetal
central nervous
system
– Maturity of lungs
NEUROLOGICAL SYSTEM
• Formed during the 3rd week
• Respiratory effort
• Swallowing
• Fetal movement felt
(Quickening)
• Sucking
18 1/2 WKS
12 1/2 WKS
16-20 WKS
29 WKS
IMMUNE SYSTEM
• Passive immunity - FROM MOM
• Active immunity - FROM FETUS
What Now?
Using your notes for support, work
with a partner to fill out the activity
handout entitled “When’s That”?
Be prepared to discuss your answers
with the class. 