Foetal development by Yagnaeshvar Venkatesan

A PROJECT REPORT ON
FOETAL DEVELOPMENT.
______________
SUBMITTED BY
V.SRI YAGNAESHVAR
CLASS - XII
Academic Year 2020-2021
UNDER THE GUIDANCE OF
Mrs.S.JAYALAKSHMI, M.Sc, B.Ed
DEPARTMENT OF BIOLOGY
MAHARISHI VIDYA MANDIR
RAJAPALAYAM

RAJAPALAYAM
CERTIFICATE
This is certify that V.SRI YAGNAESHVAR of Class XII has prepared
the report on the project entitled “FOETAL DEVELOPMENT”. The
report is the result of his effort and endeavours. The report is found
worthly of acceptance as final project report for the subject Biology
of Class XII. He has prepared the report under my guidance.
Mrs.S.JAYALAKSHMI, M.Sc, B.Ed
RAJAPALAYAM

MAHARISHI VIDYA MINDIR
RAJAPALAYAM
CERTIFICATE
The project report entitled “FOETAL DEVELOPMENT”
Submitted by V.SRI YAGNAESHVAR of Class XII for the
CBSE Senior Secondary School Examination class XII of
Biology at Maharishi Vidya Mandir, Rajapalayam has been
examined.
SIGNATURE OF SIGNATURE OF SIGNATURE OF
PRINCIPAL INTERNAL EXAMINER EXTERNAL EXAMINER

ACKNOWLEDGEMENT
I would like to express a deep sense of thanks and graduate to my
project guide Mrs S, Jayalakshmi for guiding me immensely through the
course of project. She always evinced keen interest in my work. Her
constructive advice and constant motivation have been responsible for
the successful completion of this project.
My sincere thanks goes to Shri V. Suresh our Principal sir, for this
coordination in extending every possible support for the completion of
this project.
I also thanks to my parents to their motivation and support. I
must thanks to all who supports for the completion of this
project.
Last but not least, I would like to thanks all those who has helped
directly or indirectly toward the completion of this project.
V.SRI YAGNAESHVAR
CLASS XII

CONTENTS
1. INTRODUCTION
2. FETAL LENGTH & WEIGHT
3. AGE OF THE FOETUS
4. GROWTH OF THE FOETUS
5. FACTORS AFFECTING FETAL
FROWTH
6. PARTS OF FOETAL
DEVELOPMENT
7. TIME PERIOD – GESTATION OF
FOETAL DEVELOPMENT
8. FOETUS ABNORMALITIES /
DISORDERS AND TREATING IT
IN FOETUS
9. FOETUS –CIRCUALTION
10. FOETUS –NOTOCHORD
11. CONCLUSION
12. BIBLOGRAPHY

1. INTRODUCTION:
 From a tiny cluster of cells to a bouncing baby - foetal development is an amazing process.
 At the end of the 8th week after fertilization (10 weeks of pregnancy), the embryo is considered a foetus.
 During this period less tissue differentiation occurs, but growth and maturation of tissues formed during the
embryonic period occurs.
 Prenatal or antenatal development is the process in which embryo or foetus gestates during pregnancy from
fertilization until birth. Thus, the growth and maturation of the foetus in uterus is called as Foetal
Development.
 Embryology, the study of the formation and development of an embryo and foetus..
2. FETAL LENGTH & WEIGHT :
 In the earlier weeks, it is expressed as the measurement from the vertex to the coccy [crown –rump
length(CRL)].
 While after mid-pregnancy (20 week onwards), the measurement of the foetus is determined from the
vertex to the heel (crown heel length).
3. AGE OF THE FETUS:-
 Gestational age – (based on a 28 day cycle) is calculated from the first day of a woman’s last menstrual
period. Gestational age is also referred to as number of weeks pregnant.
 About 280 days, or 40 weeks, between the first day of the last menstrual period and the birth of the infant.
WEEK FOETUS WEIGHT FOETUS LENGTH
4 Less than 0.04 oz- ounce About 0.014 to 0.04 in.
5 Less than 0.04 oz. About 0.05 inches.
6 Less than 0.04 oz About 1/8 inches.
7 less than 0.04 oz. about .5 inches.
8 less than 0.04 oz. about 0.63 inches.
9 About .07 oz. About .9 inches.
10 0.14 oz 1.22 inches.
11 0.25 oz. 1.61 in.

4.GROWTH OF THE FETUS:-
 The fetal growth shows a linear increase until the 37 weeks, thereafter it tends to plateau.
 It is controlled by genetic factors in the first half and by the environmental factors in the second half of
pregnancy.
 Actually, the average fetal weight varies from 2.5 kg to 3.5 kg.(INDIA)
5. FACTORS AFFECTING FETAL GROWTH:
 Predominant control is genetic factor.
 Fetal sex: If it is a male foetus then it weighs 100 to 200 gm more than a female Foetus (European babies
weigh more than Indian babies).
 Maternal age- mothers over 35 years of age tend to have smaller babies. Incidence of congenital anomaly is
also higher.
 Socio-economic and nutritional- average weight of babies born to lower social class tends to be lower
 Parental height and weight- tall and heavier mothers have heavier babies
 Birth order-fetal weight rises from first to second pregnancy
 Smoking in pregnancy reduces mean birth weight by 200-400g, Alcoholism reduces fertilization process.

6. PARTS OF FOETAL DEVELOPMENT:
7. TIME PERIOD FOR FOETAL DEVELOPMENT:
 The distinct changes in the Foetus will be observed during each trimester.
 Traditionally, we think of a pregnancy as a ten-month process. However, this isn’t always the case.
 A full-term pregnancy is 40 weeks, or 280 days. They’re also certain complications in newborns. Babies that
are born in the early term period or before may have a higher risk of breathing, hearing or learning issues
than babies born a few weeks later in the full term time frame
 This is divided into three Stages: the Pre-embryonic Stage begins with conception and ends on gestational
day 14 (Fertilization to 2-3 weeks), the Embryonic Stage encompasses gestational weeks 4 to 8 and the
remainder of the pregnancy is known as the Fetal Stage (9 Weeks to birth).
 Also foetal development is divided into three trimesters: i) First trimester involves week 1 to 12.
ii) Second trimester involves week 13 to 24. iii) Third trimester involves weeks 25 to 40.
FIRST TRIMESTER
i. WEEK – 1
 Fertilization of the ovum to form a zygote
 Mitotic cellular divisions starts as the zygote moves through the Isthmus of the oviduct called Cleavage
towards the uterus and forms 2,4,8,16 daughter cells called Blastomers.
 The embryo with 8 to 16 blastomers is called Morula.

ii. WEEK – 2
 Embryo develops into two cell layers (trophoblast and blastocyst)
 Trophoblast cells surrounding the embryonic cells proliferate and invade deeper into the uterine lining.
 The Morula continues to divide and transforms into Blastocyst as it moves further into the uterus.
 The blastomers in the blastocyst are arranged into an outer layer called Trophoblast and an inner group of
cells attached to tropoblast called the Inner cell mass.
 They will eventually form the placenta and embryonic membranes.
 The blastocyst is fully implanted day 7-12 fertilization.
 The embryonic cells flatten into a disk. Primary chorionic villi forms and Amniotic cavity appears.
 At this time , the blastocyst undergoes morphological changes to produce a bilaminar embryonic disc, giving
rise to the germ layers that ultimately form future tissues and organs of embryo.
iii. WEEK – 3
iv.
 Heart is formed.
 The neural tube (rudiment of brain and spinal cord) and notochord
(rudiments of the vertebra) develops.
 Starts forming gastro intestinal tract
 Primitive blood cells develop.

IV. WEEK – 4
 The heart bulges, further develops, and begins to beat in a regular rhythm.
 The neural tube closes.
 The ears begin to form as otic pits.
 Arm buds and tail are visible.
 Pulmonary primordium, the first traits of the lung appear.
 The first traits of the liver appear
 Neural tube, which forms the brain and spinal cord, closes by the fourth week
V. WEEK – 5
 The embryo measures 8 mm (1/4 inch) in length.
 Lens pits and optic cups form the start of the developing eye.
 Nasal pits are formed.
 The brain divides into 5 vesicles
 Leg buds form and hands form as flat paddles on the arms
 Skeleton primitively gets formed.

VI. WEEK – 6
 The embryo measure 13 mm (1/2 inch) in length.
 Lungs begin to form.
 The brain continues to develop.
 Mouth and palate begin to take form
 Arms and legs have lengthened with foot and hand areas
distinguishable.
 The hands and feet have digit, but may still be webbed.
 The lymphatic system begins to develop
 Rudiments of the eyes, ears, and nose appear
 Lung buds are developing
 Primitive intestinal tract is developing
 Primitive cardiovascular system is functioning
VII. WEEK – 7
 Most of the growth occurs in head because new brain
cells are generated at the rate of 100 per minute.
 Mouth and tongue begins to form.
 Kidneys starts to develop and does primitive
functions like waste management in foetus.
 The Umbilical cord is taking shape.
 This lifeline connects the baby to the Placenta to
carry oxygenated blood and nutrients.
 They look like paddles with webbed limbs.
 The Brain just starts its differentiation into Fore
brain, Hind brain , Mid brain.
 The shape resembles like a Blueberry
 Eye lenses begin to form but not completely.
VIII. WEEK – 8
 Eyelids and ears are forming,
 Tip of the nose is visible.
 The fingers and toes grow longer and more distinct.
 The arms and legs are well formed.
 But arms become flexible at elbows and wrists.
 Eye pigments starts to develop.
 As the intestines form, they start to take up space in the umbilical cord because there`s not enough space
in baby`s abdomen.
 Beginning of neck and upper lip is formed.

IX. WEEK – 9
 The middle of this period (9 weeks) marks the end of the
embryonic period and the beginning of the fetal period.
 Baby`s skeleton starts to become harden.
 Hardening of bones (ossification) begins with the formation
of cartilage.
 Her fingers, toes, knees and elbows develop.
 Nipples and hair follicles forms.
 Pancreas, Bile ducts, Gallbladder and anus forms.
X. WEEK – 10
 Foetus takes the shape of human being.
 All the baby`s major body organs have started to
form.
Small indentations on the legs are developing into
knees and ankles.
Baby`s nose, mouth , eyes are taking shape.
Tooth buds and caps are becoming recognizable.
Fingers and toes lose their web look and get longer.
The outer ears are forming and moving into place on
head.
Baby`s size is big as a strawberry.
Vocal cords are formed.

XI. WEEK – 11
 Ear gets final shape.
 Fingernail and Toenail beds begin to develop this week.
 Baby`s size is similar fig.
 Nasal passages are open, tongue is present and tooth buds
continue forming.
 Heart beat will be audible.
 Thin skin forms.
 Baby`s face is broad .
 RBC`s Form.
 By the end of 11th
week, genitals begin to form.
XII. WEEK – 12
 Fetal digestive system is beginning to flex its muscles .
 Bone marrow is busy making WBC .
 Baby`s size is similar to lemon.
 Eyelids are fully formed.
 Baby starts to moves slowly inside uterus .
 The intestines grows and protrude into umbilical cord ,
move back into abdominal cavity.
 End of 1st
Trimester period.
 Fingers will soon begin to open and close, toes will curl,
and the mouth will make sucking movements.
SECOND TRIMESTER
XIII. WEEK – 13
 The baby's tiny fingers now have fingerprints, and her veins and organs are clearly visible through her skin.
 If the developing foetus is a girl, then the ovaries contain
more than 2 million eggs.
 Your baby is the size ofa pea pod.
 Baby's bladder can be seen with an ultrasound, and the
kidneys are producing urine that becomes part of the
amniotic fluid.
 The placenta provides the baby with oxygen and
nutrients.
 It also filters out waste. While it is now fully functioning,
it continues to grow and change throughout pregnancy

XIV. WEEK – 14
 The intestines are already working onthe first bowel
movement(called meconium)
 The liver is making bile.
 The thyroid gland is beginning to make hormones.
 Brain impulses have begun
XV. WEEK – 15
 The baby's eyelids are still fused shut, but can sense light
 Ultrasounds done this week may reveal the baby's sex.
 Your baby is the size ofan apple.
 Now the baby can make whole-body movements, move their
arms and legs, stretch, and make breathing motions.
 The outer part of the baby’s ears is growing and steadily
becoming more recognizable.
 Meanwhile, the inner ear continues to develop. But the baby
can't quite hear .
 Bones continue to ossify or harden.
 Some bones in the skull, spine, and shoulders, along with the
collar bone and long bones, have already begun the process.
The bones of the hands and feet are also hardening during this week
XVI. WEEK – 16
 The baby's heart is beating around 150 to 180 times per minute, and it's pumping approximately 25 quarts (24
litres) of blood a day.
 Baby's taste buds and taste pores are developed and
working by this week.
 So, the baby can taste the amniotic fluid as it enters the
mouth.
 Since amniotic fluid takes on flavours of your diet, the baby
can now start developing taste preferences while in the
womb.
 Muscles and bones are continuing to grow and complete
your baby's skeleton.
 The baby's head is more erect or straight and in line with
the body now.
 The first eye movements are seen beneath the eyelids
between 16 and 18 weeks; once eye motions start, babies
start to touch their eyelids.
 The baby may begin to hear limited sounds this week.

XVII. WEEK – 17
 The baby is making adipose or fat tissue.
 Fat cells first appear in the face, neck, breast, and stomach
wall. Then, fat is added to the back, shoulders, arms, legs, and
chest.
 Fat tissue has many important functions, such as storing
energy, insulating the body, protecting the organs, and filling out
the baby’s features.
 The umbilical cordandplacentaare steadily growing.
 The umbilical cord is getting thicker and longer to nourish
your baby, while the placenta is expanding and increasing
circulation to deliver nutrients and oxygen to the baby.
 Now baby is the size ofa turnip.
XVIII.WEEK – 18
 Your baby is the size ofa bell pepper.
 The internal clock that regulates sleeping and waking throughout the day is developing and will become more
organized as the baby continues to grow. Sex organs structures are formed.
 Internally, a protective coating of myelin is forming around his nerves.
 Myelin is a mix of fat and protein that insulates and protects nerve cells in the nervous system, including the
brain and the spinal cord. It also helps messages travel along the nerve pathways faster..
XIX. WEEK – 19
 A protective covering is beginning to form on the baby's skin.
 This thick, white, wax-like coating is called vernix caseosa.
 Vernix has many important functions.
 Here are some of the things vernix does for your baby while they are in the womb.

 Acts as a lubricant to help your baby pass through
the birth canal with more ease
 Creates a waterproof layer that protects your
baby's skin from the amniotic fluid
 Helps prevent infection, Helps your baby to
regulate body temperature
 Moisturizes your baby's skin
 Promotes wound healing
 On top of your baby's head, the hair canal or tunnel in the skin
that holds the hair is now fully formed.
 Hair follicles have already started developing, and soft, fine hair
calledlanugois beginning to appear.
 The baby has already started developing white fat tissue, which stores energy. Now, they are making brown
fat.
 Babies need brown fat to keep warm once they leave the womb.
XX. WEEK – 20
 By week 20, baby's reproductive system has developed significantly.
Female: The development ofhuman egg cellsbegins long before birth. The number of eggs in the
ovaries is at its peak around 20 weeks, with about six to seven million eggs. This number decreases from this
point on and continues to go down throughout life.
Male: The testes are still in the abdomen, preparing to move to the
inguinal area (groin) to begin their descent. However, the testes typically
do not descend into the scrotum until the third trimester.
 Hair follicles are getting longer.
 Eccrine sweat glands begin to form.
 The gallbladder is producing bile, which helps to digest nutrients
 Your baby is the size ofa banana.
XXI. WEEK – 21
 The placenta is still delivering the majority of the baby's nutrients.
 But, the baby's digestive system is developing and maturing
to take over after birth.
 The pancreas is beginning to make enzymes that break
down food for digestion.
 The small intestine is growing longer and absorbing
nutrients from theamniotic fluidthat the baby swallows.
 Up until this point, the baby's liver made most of the RBC.
 But now, their bone marrow is becoming a major
contributor
 The baby's movements have gone from flutters to full-on kicks and jabs against the walls of your womb.
 Your baby is the size ofa carrot.

XXII. WEEK – 22
 The baby’stear ductsare developing.
By 22 weeks, thebaby's heartbeatcan usually be heard through astethoscope.
 The difference can be seen between mom and baby's heartbeat by the
number of beats in a minute.
 An adult's heart rate is between 60 and 100 beats per minute.
 The baby's heart beats faster & is between 110–160 beats per minute.
 The baby is growing rapidly and taking in more calcium for healthy
development, especially of the bones and teeth.
 The skeleton continues to harden.
 Baby's hands can now move independently. Baby can touch one hand
with the other, cross the hands, and can even grasp the umbilical cord.
XXIII. WEEK – 23
 The baby's brain is developing very quickly during this time.
 A baby can respond to light as early as 23 weeks. The baby's fingernails now reach the tips of the fingers.
 Survival Outside the Womb
 It is very rare for babies born before
23 weeks but these early are still not ready for life
outside the womb.
 However,extremely premature
babiesborn during the 23rd week of pregnancy do
have achance of surviving.
 They require a high level of
specialized care in a neonatal intensive care unit
(NICU).
 Research shows that in developed
countries, between 23% and 27% of babies born at
23 weeks survive to go home with their family.
XXIV. WEEK – 24
 End of 2nd
trimester.
 The baby is in rapid-growth mode, putting on about 3 to 6 ounces each week.
Part of that weight gain is coming from the addition of fat.
 The branches of the baby’s lungs are forming, as well as the cells that make
surfactant, a natural substance that lines the tiny air sacs (called alveoli) in the lungs
to make breathing possible.
 While a small amount of surfactant is now present, the lungs are still
immature. Babies born this early have hard time breathing.
 Your baby’s inner ear—which controls hearing and balance—is continuing to
develop.
 The eyelids have separated, and are beginning to take their final shape.
 The bone marrow will take over as the primary producer of baby's RBC

THIRD TRIMESTER
XXV. WEEK 25
 The part of the nose that can sense smell is now functioning.
 The baby can now smell
odours and scents in theamniotic fluid.
 There are four stages offetal
lung development.
 This week, the second stage
(the canalicular stage) is complete.
 The branches of the lungs, the
small passageways, and the capillaries
(which are the smallest blood vessels)
have formed.
 There are still two more
stages of development to go, though
the last stage continues into childhood.
XXVI. WEEK 26
 If a developing foetus is a boy then the testicles may
begin to descend into the scrotum this week.
 The baby's intestines are absorbing more and more
nutrients from the amniotic fluid and producing
enzymes to break down nutrients such as sugars,
proteins, and fats for digestion.
 All the parts of the baby's eyes are formed.
 The baby even has visible eyebrows and eyelashes.
 Baby is beginning to display thestartle or moro
reflexas well as the palmer (hand) and plantar
(foot) grasp, all reflexes you'll see them perform as
newborns.
XXVII. WEEK 27
 The baby’s brain is now more active than ever.
 The neurons and synapses (where the brain cells meet) are
forming and making a system of complex connections
throughout the areas of the brain. The baby's lungs are
continuing to mature.
 The tiny air sacs in the lungs (called alveoli) are expanding to
help the baby take in and exchange air after birth;
meanwhile, the cells of the lungs are making the small
amount of surfactant necessary to keep the alveoli from
collapsing.
 Now the baby is also taking "practice breaths" of amniotic
fluid—a practice that is an important part of their lung
development.

 The baby is spending about 10% to 20% of their time doing practice breaths.
XXVIII. WEEK 28
 The brain tissue is developing the ridges and furrows that give the brain its well-known grooved and folded
appearance.
 The higher frequency of eye
movements is associated with
REM sleep andhealthy brain
development.
 The umbilical cord carries blood
between the placenta and your
baby. It supplies your baby with
nutrients and oxygen and aids the
removal of their waste products.
 The umbilical cord was fully
formed byweek 12, but it has
continued to grow in both
diameter and length.
 By the time afull-term babyis born, the umbilical cord will be between 1 and 3 feet (30–100 centimeters) long
and over 1/2 inch (16 millimeters) wide.
XXIX. WEEK 29
 The baby's muscles and lungs are busy getting ready
to function in the outside world, and the head is
growing to make room for his developing brain.
 The baby is continuing to add fat and muscle. Baby's
skin is also maturing and getting thicker.
 The amount oflanugo(fine hair) covering baby's body
has peaked and will now begin to fall out.
 The main growth of baby's bones happens from the
second trimester onward.
 Baby will increase their intake of calcium as their
bones get harder and stronger.
XXX. WEEK 30
 Baby is surrounded by a pint and a half of amniotic
fluid, although there will be less of it as she grows and
claims more space inside your uterus.
 The baby is the size ofa large cabbage.
 The baby's major body systems are all formed and
are in the process of maturing. Now it is time for the baby
to start gaining weight very quickly to prepare for life
outside the womb.
 Also the baby has probably been getting the hiccups
that are common in the last trimester of pregnancy.

 Those little rhythmic movements are contractions of the respiratory muscles.
 Studies show that as early as 10 weeks before delivery, hiccups stimulate the brain and may play an important
part in its development.
XXXI. WEEK 31
 The baby can now turn his head from side to side.
 A protective layer of fat is accumulating under his skin, filling out
his arms and legs.
 The baby is the size ofa coconut.
 Ultrasound can pick up the tiny movements of the baby's eyelids
blinking.
 Research shows that babies at 31 weeks blink very slowly—
approximately 6 to 15 times an hour (compared to adults, who blink
19–20 times per minute).
 As the lungs continue to mature, the baby
is still working on those breathing skills
 Breathing movements increase from 30%
to 40% after 30 weeks.
XXXII. WEEK 32
 The baby started to develop brown fat -the type of fat
needed to keep warm after leaving the womb.
 The baby's body has also increased production of a
protein and an enzyme necessary for generating
body heat, which means they can now regulate their
body temperature better.
 Most babies display thestartle or Moro reflexby this
weeks.
 A loud noise or a movement can cause the baby to
appear startled, suddenly throw their arms and legs
away from their body then bring them back in. Babies
are born with the startle reflex, but it disappears a
few months after birth.
 The baby is also showing evidence of cycling through
stages of sleep and wake times, and their brain
activity now shows active sleep.
 By 32 weeks, 85% of babies are in the head-down
position.

XXXIII. WEEK 33
 The bones in your baby's skull aren't fused yet.
 Baby’s bones are now fully developed, but still a bit soft
and malleable, especially the plates in their skull.
 That allows them to shift as his head squeezes through the
birth canal.
 They won't fully fuse until adulthood.
 Your baby is the size ofa pineapple.
 These bones need to remain pliable in order to pass
through the narrow birth canal.
 In fact, one or two spots will remain soft even up to a year
after your baby is born.
 These areas, calledfontanelles, are normal gaps that allow
room for the baby’s brain to continue developing.
 The baby is beginning to coordinate and practice sucking
and swallowing.
 The baby can also demonstrate therooting reflexby
turning their head and opening their mouth in response to a touch or stimulation of the cheek.
XXXIV. WEEK 34
 Baby's central nervous system is maturing.
 Babies born between 34 and 37 weeks who have no other health problems usually do well in the long run.
 That thick, waxy, cream cheese-like coating covering the baby's skin has been thickening until now.
 Thevernixstarts coming off into the amniotic fluid.
 Scientists believe that when babies swallow the vernix in the fluid, it may help with the development of their
stomach and intestines.
 The amniotic fluid that the baby is living in is at its peak around 34 weeks
 . There are about 1 1/2 pints (800 milliliters) of fluid surrounding baby, and baby is moving in the amniotic
fluid, swallowing it, and "breathing" it in.
 Amniotic fluid contributes to the development of the baby's muscles and bones, digestive system, and lungs.

XXXV. WEEK 35 – WEEk 37
 The baby's kidneys are fully developed, and his liver
can process some waste products by in between
week 35 to week 37.
 The baby has been getting ready to take feedings
after birth by practicing their sucking and swallowing
skills for a few weeks.
 The coordination of sucking and swallowing is
complete by 35 to 37 weeks.
 Human pregnancy lasts approximately 40 weeks.
 When the amount of time or term of pregnancy is
complete, a baby is considered ready for birth.
 Pregnancy used to be considered "term" anywhere
from 37 to 42 weeks.
XXXVI. WEEK 38 – WEEk 40
 The baby`s irises are not fully pigmented, so if they are born with blue eyes, they could change to a darker
color up until their are about a year old.
 The baby's final eye color will depend on
how much of a protein called melanin your
baby produces.
 But, it can take up to a year for the iris, or
the part of the eye that has color, to reach
its final color of brown, blue, green, hazel,
or somewhere in between.
 The baby's physical development is
complete, but he's still busy putting on fat
he'll need to help regulate his body
temperature in the outside world.
 By the last 2 weeks of delivery, baby is
shedding thesoft, fine hair(known as
lanugo) that covers their body in utero.
 Most of this hair is typically gone before a
full-term baby is born—although some hair
may remain on the baby's shoulders and
arms.
 This week, your baby is right on target at
40 weeks, which is considered "full term."
Babies born at full term encounter fewer
risks and generally have better health outcomes.

8. FOETUS ABNORMALITIES / DISORDERS AND TREATING IT IN FOETUS:
 Foetal abnormalitiesare conditions that affect afoetusorembryoand may be fatal or cause disease after
birth.
 Mutations in a person`s genes can cause a medical condition called a Genetic disorder.
 Genetic disorders occur when a problem in the baby’s chromosomes or genes causes physical abnormalities
or illnesses.
 Changes such as Methylation of DNA may cause certain maternal or paternal alleles to be expressed to
different degress.
Factors responsible for genetic disorders:
a) Family history of a genetic disorder (pedigree analysis)
b) One parent has a chromosomal abnormality
c) Advanced maternal age (35 or older)
d) Advanced paternal age (40 or older)
e) Matrilateral marriages (cousin marriages)
Detection of disorders:
 Screening tests– these tests check the risk of your baby having certain genetic disorders
a. Carrier screeningis a blood test that tries to determine if either parent carries a genetic change
for inherited disorders that could be passed on to the baby. It can also be performed on a saliva
sample.
b. PCR : Polymerase Chain Reaction - Amplification of DNA isolated from Chorionic villi , before
eventual DNA sequencing can be carried out.
 Non-invasive Prenatal Testing (NIPT) or cell-free DNA screeningis a blood test that checks DNA from the
placenta that is found in the mother’s blood.
 Diagnostic tests– these tests can detect if certain genetic disorders are actually present in the baby
a. Routine diagnostic tests include: Chorionic villi sampling tests a sample of tissue taken from the
placenta in the first trimester.
b. Amniocentesis: Tests a sample of the amniotic fluid taken from the womb in the second trimester
to find such as cystic fibrosis or Down syndrome.

Types of Disorders
There are several types of disorders that arises in Foetus:
1. Single gene disordersoccur when a change in one gene causes a disease.
 Examples include cystic fibrosis, sickle cell anaemia, Tay-Sachs disease, haemophilia, and Marfan
syndrome.
2. Chromosomal abnormalitiesoccur where there are missing or extra chromosomes, or pieces of
chromosomes. Chromosome abnormalities can be inherited from a parent or they can happen by chance.
 Examples, Down syndrome, the most common chromosomal abnormality, is caused by an extra
chromosome number 21.
 Klinefelter`s syndrome , Turners syndrome are examples of these diseases.
3. Multifactorial or complex disordersare caused by a combination of genetic predispositions and
environmental factors, which makes it harder to predict who may be at risk.
 Examples include heart defects, cleft lip or cleft palate, and spina bifida.
4. Teratogenic disordersoccur when the baby is exposed to substances during pregnancy that cause
abnormalities, otherwise known as “teratogens.”
 Babies are very sensitive in the first trimester, when all of the organs are developing.
 Teratogens include alcohol, drugs, lead, high levels of radiation exposure, and certain
medications, infections and toxic substances.
Treatment of Foetal Disorders:
1. Molecular Diagnosis:
 The process of identifying a disorder by studying molecules, such as proteins , DNA and Tissue
or fluid .
 Detects the health condition first and used for treating a syndrome.
2. Foetal Therapy:
 It is defined as Therapeutic intervention for the purpose of correcting /
treating a fetal anomaly is called Fetal Therapy.
 It is also known as Foetal treatment.
 Treatment of abnormalities in Uterus.
 Foetal therapy is developed worldwide as a consequence of advances in
prenatal diagnosis.

DISORDER – 1 : SPINA BIFIDA
 Causes and Defect : Spina
bifidais a birth defect that
occurs when the spine and
spinal cord don't form
properly. It's a type of neural
tube defect.
 Treatment : Spinal Surgery
with Spinal fusion is
proceeded to treat this
disease.
DISORDER – 2 : CLEFT PALATE
 Causes and Defect : Acleft palateis an opening or split
in the roof of the mouth that occurs when the tissue doesn't fuse together
during development in the womb.
 Treatment : Surgery usually occurs but also speech
therapy cures it.
DISORDER – 3 : ESOPHAGE ATRESIA
 Causes and Defect : Esophageal
atresiais a birth defect in which part of
a baby'sesophagus(the tube that
connects the mouth to the stomach)
does not develop properly.Esophageal
atresiais a birth defect of the
swallowing tube (esophagus) that
connects the mouth to the stomach.
 Treatment : Treatmentconsists in
surgical ligation of the fistula
andesophagealanastomosis of the two
pouches by conventional thoracotomy or
by thoracoscopic approach..

DISORDER – 4 : ANENCEPHALY
 Causes and Defect : Anencephalyis a serious defect in
which a foetus is found without parts of the brain and
skull. It is a type of neural tube defect (NTD).
 Treatment : There is
notreatmentorcureforanencephaly. The Foetus with
such disorder won’t live but in rare cases survives.
DISORDER – 5 : VENTRICULAR SEPTAL DEFECT
 Causes and Defect: Aventricular septal defectis an abnormal opening (hole) in the heart that forms
between the heart's lower pumping chambers (ventricles), as shown in the heart on the right. This
allows oxygen-rich and oxygen-poor blood to mix. A normal heart is shown on the left.
 Treatment : Plugging or patching the abnormal opening between the ventricles by cardiologists.
FACT : IF THE FOETUS IS FOUND WITH DISORDERS & USUALLY PARENTS ABORT SUCH FOETUS BUT RARELY 2-3%
PARENTS DONT DO SUCH ACTIVITIES.
7. FOETUS – GASTRULATION

8. FOETUS –CIRCUALTION
9. FOETUS –NOTOCHORD
10. CONCLUSION
I conclude the Foetal development as it first seems to be small to the average person but in reality, it is one of
the most vital process for the population growth. It sets the stages for a soon to be infant, child, teenager,
and then a adult. The life is like a book and each stages of development are the chapters that it consists.
Environmental events and biology interacts to determine a healthy foetus. It is because the foetus is most
vulnerable during the 1st
trimester, as all the major organs and body systems are forming and can be damaged
if the foetus is exposed to drugs, infectious agents, radiation , tobacco and other toxic substances. Thus, it is
important for the doctors to know the normal and abnormal ranges of foetus growth and with proper
diagnosis, treatment and planning the healthy foetus can be developed successfully. .

Bibliography
1. NCERT BOOK- CLASS XII BIOLOGY (PRIMARY SOURCE).
2. VERMA.P.S, TYAGI. B.S, AGARWAL. V.K. (1979), ANIMAL PHYSIOLOGY.
3. NIRANJANBHATTACHARYA, PHILLIP G.STUBBLEFIELD (1984) HUMAN FOETAL GROWTH
AND DEVELOPMENT.
4. SARADA SUBRAHMANYAM, K MADHAVANKUTTY (1990) , TEXT BOOK OF HUMAN
PHYSIOLOGY.
5. MANI .A.S (2001) , ESSENTIALS OF HUMAN ANATOMY & PHYSIOLOGY.
Outside a Sidra hospital in Qatar

Foetal development by Yagnaeshvar Venkatesan

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