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HUMAN FETAL PERIOD –
ASSESSMENT OF FETAL
DEFECTS
BY: DR TATHEER ZAHRA
ASSISTANT PROFESSOR ANATOMY
FETAL PERIODA final phase of prenatal life includes the 3rd to 10th
lunar months (period of fetus).
In it differentiation continues and organs become
competent to assume their specialized functions.
FETAL PERIODEarly fetal period
- 8-16 weeks
Middle fetal period
- 17-30 weeks
Late fetal period
- 31-38 weeks
THIRD MONTH (9-12 wks)
HEAD:
Disproportionately large
Makes up nearly half of the fetus' size
EYES:
Directed forward
Close and will not reopen until about the 28th week
EARS:
Rise to eye level
PREUMBLICAL HERNIATION: Reduced
FACE: Is well formed
LIMBS: Are long and thin
OSSIFICATION CENTER:
NAILS: Begin forming
GENITALS: Appear well differentiated
RBC’S: Are produced in the liver
FIST: The baby can make a fist with its fingers
TOOTH BUDS: Appear
URINE: Start forming
FOURTH MONTH (13-16 wks)
FACE:
Broad
Human appearance
EYES:
Directed forward
Eyelids fused
UMBLICAL CORD:
Attaches higher on abdominal wall
13 wks
FETAL SKIN: Is almost transparent
LANUGO: Develops on the head
MECONIUM: Is made in the intestinal tract
LIVER AND PANCREAS: Produce fluid
secretions
ACTIVE MOVEMENTS: Begins
SUCKING MOTIONS: Are made with the
mouth
FIFTH MONTH (17-20 wks)
Downy hairs (LANUGO)
Head hairs
Fetal movements (QUICKENING)
Mother may feel a FLUTTERING in the lower
abdomen
Baby can HEAR
VERNIX CASEOSA
EYEBROWS AND LASHES: Appear
NAILS: Appear on fingers and toes
FETAL HEARTBEAT: Can be heard with a
stethoscope
BROWN FAT
SEX ORGANS
SIXTH MONTH (21-24 wks)
EYEBROWS & EYELASHES : Well defined
SKIN: Wrinkled, pink to red, more translucent
BODY: Lean but better proportioned
FOOTPRINTS AND FINGERPRINTS: Forming
BONE MARROW:
AIR SACS:
SURFACTANT:
FAT:
SEVENTH MONTH (25-28 wks)
FETUS LOOKS: Like dried up old person
SKIN: Red, Wrinkled, Covered with vernix caseosa
EYELIDS: Reopen
TOE NAILS:
CNS: Developed to control some body functions
RESPIRATORY SYSTEM: Immature
EIGHT MONTH (29-32 wks)
SUBCUTANEOUS FAT:
Depositing
Rapid ↑ in the amount of body fat (8%)
TESTIS: Begin to invade the scrotum
INFANTS OF THIS AGE, BORN
PREMATURELY: May survive with proper care
RHYTHMIC BREATHING MOVEMENTS: Occur, but lungs are not fully mature
BONES: Are fully developed, but still soft and
pliable
STORAGE: Baby's body begins storing iron,
calcium, and phosphorus
PUPILLARY LIGHT REFLEX
NINTH MONTH (33-36 wks)
SKIN:
Dull redness of the skin fades
Wrinkles smooth out
Lanugo begins to disappear
BODY AND LIMBS:
Become rounded
Body fat increases
Fingernails reach the end of the fingertips
FULL TERM
BODY: Plump
LIMBS: Upper limbs are slightly longer than lower
limbs
UMBLICAL CORD: At the centre of the abdomen
SKIN: Lost lanugo hair coat, but still smeared with
vernix caseosa
AVERAGE WEIGHT: 7 pounds
AVERAGE HEIGHT: 20 inches
TESTIS: Usually in the scrotum
HEAD & ABDOMINAL CIRCUMFERENCE
NAILS: Projects beyond the fingers & the tips of toes
BREAST BUDS: Small breast buds are present on
both sexes
THORAX: Prominent
HEAD HAIR: Is now coarse and thicker
WHITE FAT: Approximately 16% of body weight
GROWTH IN LENGTH & WEIGHT
DURING FETAL PERIOD
Age (weeks) CRL (cm) Weight (g)
9 -12 5 - 8 10 - 45
13 - 16 9 - 14 60 - 200
17 - 20 15 - 19 250 - 450
21 - 24 20 - 23 500 - 820
25 - 28 24 - 27 900 - 1300
29 - 32 28 - 30 1400 - 2100
33 - 36 31 - 34 2200 - 2900
37 - 38 35 - 36 3000 - 3400
DEVELOPMENTAL HORIZONS
DURING FETAL LIFE
EVENTS AGE (weeks)
Taste buds appear 7
Swallowing 10
Respiratory movements 14 – 16
Sucking movements 24
Some sounds can be heard 24 – 26
Eyes sensitive to light 28
To
32
wk
s
Less than 1/10th of an
inch long
Less than 1 inch long
About 16.5–18 inches long, weighs 4 to 5 pounds
19 inches long, weighs 6 pounds
About 5.5 inches long,
weighs about 4 ounces
About 10-12 inches long,
weighs 1/2 to 1 pound
About 11-14 inches long, weighs 1 to 1.5 pounds
About 14-17 inches long, weighs 2.5
to 3 pounds
About 3 inches long,
weighs about 1 ounce
Third trimester
begins
Second trimester begins
First trimester
begins
The Three Trimesters of Prenatal
Development
FACTORS INFLUENCING FETAL
GROWTH
MULTIPLE PREGNANCIES
SMOKING
ALCOHOL & ILLICIT DRUGS
UTEROPLACENTAL & FETOPLACENTAL
BLOOD FLOW
GENETIC FACTORS
PROCEDURES FOR ASSESSING
FETAL STATUS
Ultrasonography
Diagnostic
amniocentesis
α-fetoprotein assay
Spectrophotometric
studies
Chorionic villus
sampling
Sex chromatin
patterns
Cell cultures &
chromosomal
analysis
Fetal transfusion
Fetoscopy
Percutaneous
umblical cord blood
sampling
CT scan & MRI
Fetal monitoring
FETAL URETEROSTOMIES
Fetus at 21 weeks undergoing bilateral ureterostomies, the
establishment of openings of the ureter into the bladder
REFERENCES:
GRAY’S ANATOMY, 40th Edition
The Developing Human, Clinically Oriented
Embryology by KEITH L. MOORE, Latest
Edition
LANGMAN’S Embryology, Latest Edition, By
T. W. SADLER