Knowledge on fetal development will guide you to know the sequential development of fetus.

1. PREPARED BY:
SRUJANI SWETASINA DASH
NURSING TUTOR
G.N.M.SCHOOL, A.N.M.M.C.H, GAYA
FETAL DEVELOPMENT

2. OBJECTIVES
 To discuss the periods of development.
 To elaborate sequential development of fetus.

3. PERIODS OF FETAL
DEVELOPMENT
The fetal development is divided into 3 periods:
 Ovular Period- Begins from fertilization and lasts
upto 2 weeks.
 Embryonic Period- Starts from 3rd week following
fertilization and lasts upto end of 7th week.
 Fetal Period- Begins from 8th week following
fertilization until birth.

4. SEQUENTIAL DEVELOPMENT DURING
OVULAR PERIOD (0-14TH DAY)
TIME IMPORTANT EVENTS
0-Hr Fertilization
30-Hrs 2- Cell Stage (Blastomere)
40-50 Hrs 4- Cell Stage
72-Hrs (3rd Day) 16 Cell Stage
96- Hrs (4th Day) •16-64 Cell Stage (Morula),
•Morula enters uterine cavity
5th Day Blastocyst
6th-7th Day •Zona Pellucida disappears
•Interstitial Implantation occurs
8th Day •Differentiation of inner cell mass into
bilaminar embryo: Ectoderm & Endoderm
•Differentiation of Trophoblast into 2 layers:
Cytotrophoblast & Syncitiotrophoblast
10th-11th Day Interstitial Implantation completed
13th Day Primary Villi

8. SEQUENTIAL DEVELOPMENT DURING
EMBYONIC PERIOD (3RD WEEK –END OF 7TH WEEK)
TIME IMPORTANT EVENTS
16th Day Secondary Villi
21st Day •Tertiary Villi
•Fetal Heart is formed
3rd Week •Mesodermal Germ layer appears
•Neural Tube(rudiment of Brain & Spinal Cord) is formed.
•Notochord (rudiment of vertebral column) is formed
•Primitive blood cells are formed
4th Week •Heart starts to beat
•Longitudinal & transverse folding of embryonic disc which
converts embryo into curved & cylindrical form.
•Rudiments of ear (otit pits), arms (arm buds), leg (leg buds),
Facial and neck structures forms.
5th Week •Rapid brain development occurs resulting in extensive growth of
head
•Growth starts from cephalic to caudal end
•Eyes are developed with retinal pigment, lens
6th Week •Nose, mouth, palate begins to start
•Neural tube closes
•Eyelids become visible
•Placenta development begins.
7th Week •Neck region is established
•Urogenital organs begins to develop.
•Arms & legs are fully developed with clearly well defined fingers
& toes

9. SEQUENTIAL DEVELOPMENT DURING
FETAL PERIOD (8TH WEEK –UNTIL BIRTH)
TIME IMPORTANT EVENTS
8th Week •All essential structures have developed
•Embryo has distinct human characteristics and hence marks the
beginning of fetal period
•Fetus is 3 cm in length.
9th Week- 12th Week
(3rd Month)
•Intestine are fully developed
•External genitalia have male & female characteristics but not
fully dev eloped.
•Anus is formed
•Fetus can swallow, urinate, move specific parts of limbs
•Open and shut mouth
•Eyelids are fused
•Fetal heart rate can be detected by doppler
•Placenta development is completed by 12th weeks
•Fetal circulation is functioning
•Length-6 to 8 cm
•Weight- 15-30 gms
13th Week- 16th Week
(4th Month)
•Body growth accelerates
•Sex is clearly distinguishable by 14th week
•Rapid skeletal development
•Lanugo hair appears on head
•Stronger fetal movement felt by mother at the end of 16th week.
(Quickening)
•Meconium in gut
•CRL-11.5 cm
•Weight- 99 to 113 gms
contd………..

11. SEQUENTIAL DEVELOPMENT DURING
FETAL PERIOD (8TH WEEK –UNTIL BIRTH)
TIME IMPORTANT EVENTS
17th Week- 20th Week
(5th Month)
•Visible & frequent fetal movement
•Quickening may experienced by mother around 18th week (if not felt earlier)
•Vernix caeseosa covers body
•Lanugo covers body especially on back
•FHS heard on auscultation
•Skin wrinkled due to less fat
•CRL- 13 to 14 cm
•FL- 19 cm
•Weight- 435 to 465 gms
21st Week- 24th Week
(6th Month)
•Hair growth is prominent & fetus is covered with lanugo
•Skin red and wrinkled with little subcutaneous fat
•Eyebrows & eyelids are formed
•Periods of sleep & activity
•Responds to sound (startle reflex)
•Most organs are capable of functioning
•CRL- 20 cm
•FL- 26 cm
•Weight- 780- 820 gms
25th Week- 28th Week
(7th Month)
•Eyelids reopen
•Respiratory movements seen
•Lungs are developed enough to provide sufficient gas exchange
•Suckling reflex is stronger
•Body becomes proportioned
•Survival is possible if born with life support system
•CRL-22.5 cm
•FL- 30 cm
•Weight- 1200 to 1250 gms
contd………..

12. SEQUENTIAL DEVELOPMENT DURING
FETAL PERIOD (8TH WEEK –UNTIL BIRTH)
TIME IMPORTANT EVENTS
29th Week- 32nd Week
(8th Month)
•Respond to external stimuli
•Nails extend to finger tips
•Increase muscle & fat
•CRL- 27.5cm
•FL- 32 cm
•Weight- 1800 to 2100 gms
33rd Week- 36th Week
(9th Month)
•Lanugo hair disappears
•Skin is smooth
•Left testis descend into scrotum
•Increased fat makes body more rounded
•CRL- 31 cm
•FL- 35 cm
•Weight- > 2250 gms
37th Week- 40th Week
(10th Month)
•Vernix caeseosa mainly seen in skin folds and creases.
•Body organs mature.
•Lanugo fully dissappear except on shoulders.
•Both testes descended to scrotum.
•Full growth and development attained and fetus is ready to born
•CRL-35 cm
•FL- 50 cm
•Weight- > 3200 gms

14. SUMMARY
 Fetal development has 3 periods – Ovular, Embryonic and
fetal.
 Blastocyst penetrates into the compact layer of endometrium
called as implantation. This is the final stage which confirms
conception.
 Blastocyst differentiates into inner cell mass and trophoblast.
Fetus, amnion and umbilical cord develops from inner cell
mass. Placenta and chorion develops from trophoblast.
 Placenta is an essential structure which provides nourishment
to fetus and connects mother with fetus. Placental
development begins at 6th week and completed by 12th week.
 During ovular and embryonic periods, the development of all
essential organs of fetus occurs. It is a crucial period of
pregnant woman.
 Embyro has human characteristics at 8th week which marks
the beginning of fetal period.
 During fetal period the growth and development occurs.
th

15. REFERENCES
 Dutta D.C, Textbook of Obstetrics, Jaypee
Brothers Publishers, 8th Edition, Pg. No. 23- 31
 Jacob Annama, A Comprehensive Textbook of
Midwifery, Jaypee Brothers Publishers, 2nd
Edition, Pg. No. 71- 87

16. ASSIGNMENT
 Draw the schematic diagram of embryonic and fetal
development in class notebook.
 Draw or download colored diagrams as per sequential
development during embryonic and fetal development.

17. EVALUATION
 Answer following questions:
i. When does fetal period starts?
ii. Which month the body growth accelerates?
iii. The fetal movements felt by mother for the first time is called as _________.
iv. Define lanugo and vernix caeseosa?
v. Placenta development begins at _________ week and completed at __________week.
vi. Survival is possible at ___________ month if born earlier.
vii. Lanugo disappears at _________ month.
viii. When does zona pellucida disappears?
ix. Name the rudiment of brain & spinal cord.
x. Trophoblast differentiate into ______________ & ______________.
xi. Bilaminar gem disc are _______________ & ______________.
xii. Deeper penetration of blastocyst into compact layer of endometrium is called as
____________
xiii. The stage in which cells appears a cluster of ball resembling a mulberry is
______________
xiv. Name the rudiment of vertebral column.
xv. At what week the embryo has distinct human characteristics.

18. ANSWER KEY
Answer following questions:
i. When does fetal period starts?
Ans: 8th week until birth
ii. Which month the body growth accelerates?
Ans: 4th month
iii. The fetal movements felt by mother for the first time is called as Quickening
iv. Define lanugo and vernix caeseosa?
Ans: Lanugo is the first hair in fetus & fine & soft which covers the body and limbs of fetus.
Vernix caeseosa is a waxy, sticky substance coating on skin of fetus and newborn baby whci act as thermal
insulator.
v. Placenta development begins at 6th week and completed at 12th week.
vi. Survival is possible at 7th month if born earlier.
vii. Lanugo disappears at 9th month.
viii. When does zona pellucida disappears?
Ans: 6th- 7th Day
ix. Name the rudiment of brain & spinal cord.
Ans: Neural tube
x. Trophoblast differentiate into cytotrophoblast & syncitiotrophoblast.
xi. Bilaminar gem disc are ectoderm & endoderm.
xii. Deeper penetration of blastocyst into compact layer of endometrium is called as interstitial implantation
xiii. The stage in which cells appears a cluster of ball resembling a mulberry is morula.
xiv. Name the rudiment of vertebral column.
Ans: Notochord
xv. At what week the embryo has distinct human characteristics.
Ans: 8th week