6. THE STAGES OF PRE-NATAL
DEVELOPMENT
• GERMINAL PERIOD (First 2 weeks after conception)
• A. Creation of zygote
• B. Continued cell division
• C. Attachment of the zygote to the uterine wall
- Differentiation of cells already begins as inner (Blastocyts)
and outer (Trophoblast) layers of the organism are formed.
7. • EMBRYONIC PERIOD (2-8 weeks after conception)
• A. Cell differentiation intensifies
• B. Life support systems for embryo develop
• C. Organs appear
Zygote attached to the wall of the uterus
2 layers of cells are formed
- Inner layer = Endoderm
- Outer layer= Ectoderm & Mesoderm
Organogenesis- Process of organ formation during the first
2months of pre-natal development
9. • FETAL PERIOD (2months- 7 months after conception)
-growth and development continue dramatically
3 inches long
Wt. 1 ounce
-Active, moves its arms and legs,
opens and closes it’s mouth, moves its
head.
-parts of the face, upper and lower
extremities can be distinguished.
-Genitals can now be Identified.
10. 6 inches long
Wt. 4-7 ounces
-Growth spurt occurs in the
body’s lower parts
-Reflexes are stronger
-Mother feels the movement of
the embryo
-Downy hair (lanugo) covers
body
11. 12 inches long
Wt. close to a pound
- Structure of the skin
(fingernails, toenails are
formed
- More active
- Heartbeat is audible with
ordinary stethoscope
12. 14 inches long
Wt. 1 ½ pound
- Eyes and eyelids are completely
formed
- Fine layer of head covers the
head
- Grasping reflex present
- Irregular movements occur
14. 17 inches long
Wt. 5 pounds
-Subcutaneous fat is
deposited for later use.
-Responds to sounds
15. 21 inches long
Wt. 7 pounds
Organ functions actively
-vernix is present over
the entire body
-position for birth
16. TERATOLOGY AND HAZARDS
TO PRENATAL DEVELOPMENT
• TERATOLOGY- is the field that investigates the causes of
congenital (birth) defects.
• TERATOGEN- Any agent that causes a birth defect.
• From the Greek word tera “monster”
18. I. PRESCRIPTION AND NON-PRESCRIPTION
DRUGS
• ANTIBIOTICS (STREPTOMYCIN AND
TETRACYCLINE)
• DIET PILLS
• ASPIRIN- HIGH DOSAGES
19. 2. PSYCHOACTIVE DRUGS
• ARE DRUGS THAT ACT ON THE NERVOUS SYSTEM TO ALTER STATES OF
CONSCIOUSNESS, MODIFY PERCEPTIONS, AND CHANGE MOODS.
DRUGS
NICOTINE
EFFECTS
Preterm births and low
birth weights, fetal and
neonatal deaths,
respiratory problems,
sudden infant death
syndrome.
20. ALCOHOL
Fetal alcohol spectrum disorders
(FASD)
• facial deformities, defective limbs
and heart
• learning problems and many are
below average in intelligence,
while some are mentally retarded
25. • SYPHILIS (A SEXUALLY TRANSMITTED INFECTION)
• GENITAL HERPES
26. AIDS
• IS A SEXUALLY TRANSMITTED INFECTION THAT IS CAUSED BY THE HUMAN
IMMUNODEfiCIENCY VIRUS (HIV), WHICH DESTROYS THE BODY’S IMMUNE
SYSTEM. A MOTHER CAN INFECT HER OFFSPRING WITH HIV/AIDS IN THREE
WAYS:
• (1) DURING GESTATION ACROSS THE PLACENTA,
• (2) DURING DELIVERY THROUGH CONTACT WITH MATERNAL BLOOD OR
FLUIDS,
• (3) POSTPARTUM (AFTER BIRTH) THROUGH BREAST FEEDING
27. • FOLIC ACID DEFICIENCY
• NEURAL TUBE DEFECTS
• TWO TYPES
• OPEN NTDS- ANENCEPHALY, ENCEPHALOCELES, HYDRANENCEPHALY,
INIENCEPHALY, SCHIZENCEPHALY AND SPINA BIFIDA.
• CLOSED NTDS- LIPOMYELOMENINGOCELE, LIPOMENINGOCELE AND
TETHERED CORD.
• MATERNAL MALNUTRITION
30. 5. OTHER PARENTAL FACTORS
• EXPOSURE TO LEAD , RADIATION, CERTAIN PESTICIDES AND
PETROCHEMICALS
-MAY CAUSE ABNORMALITIES IN THE SPERM THAT LEAD TO MISCARRIAGE
/ DISEASES SUCH AS CHILDHOOD CANCER.
• OLDER FATHERS MAY PLACE THEIR OFFSPRING AT RISK OF CERTAIN DEFECTS