Fetal development is categorized into three periods: ovular, embryonic, and fetal, with essential organs forming during the first two periods. Key milestones include the formation of the blastocyst, the development of the heart and brain, and the onset of movement by the 8th week, marking the start of the fetal period. The fetal period sees rapid growth, culminating in readiness for birth by the 10th month.

1. PREPARED BY:SAVITA S H
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 ofTrophoblast into 2 layers:
Cytotrophoblast & Syncitiotrophoblast
10th
-11th
Day Interstitial Implantation completed
13th
Day PrimaryVilli

7. SEQUENTIAL DEVELOPMENT DURING
EMBYONIC PERIOD (3RD
WEEK –END OF 7TH
WEEK)
TIME IMPORTANT EVENTS
16th
Day SecondaryVilli
21st
Day •TertiaryVilli
•Fetal Heart is formed
3rd
Week •Mesodermal Germ layer appears
•NeuralTube(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

8. 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………..

10. 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………..

11. 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

13.  https://youtu.be/y4HK5CTVkXM?feature=shared
 https://youtu.be/y4HK5CTVkXM?feature=shared

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.
 Growth of fetus accelerates at 4th
month.
 At 10th
month fetus is ready to born.

15. REFERENCES
 Dutta D.C,Textbook of Obstetrics, Jaypee Brothers
Publishers, 8th
Edition, Pg. No. 23- 31
 Jacob Annama,A ComprehensiveTextbook 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