1. Human Development I
Chapter 4
Prenatal Development

2. Learning Objective and FCS
Standards
Learning Objective: Analyze the stages of
prenatal development, identify how
genetics plays a part in a developing fetus,
define infertility and how it is treated,
compare and contrast various birth
defects, and identify what a pregnant mom
can do to care for herself during
pregnancy.
FCS Standards: FCS 5.A, 7.A, 7.D, 5.C

3. Genetics
DNA: deoxyribonucleic acid.
 Unique for each individual, unless you are a twin!
Genes: the units that determine a human’s
inherited characteristics.
 Made up of DNA.
Chromosomes: tiny threadlike structures in the
nucleus of every cell.
 Come in 23 pairs.
 Mom and Dad each contribute one to each pair. Contains
hundreds to thousands of genes. At the moment of conception, a
baby receives 46 chromosomes.

4. Genetics
Chromosomes: tiny threadlike structures
in the nucleus of every cell.
Come in 23 pairs.
Mom and Dad each contribute one to each pair.
Contains hundreds to thousands of genes. At the
moment of conception, a baby receives 46
chromosomes.

5. Dominant and Recessive Genes
Dominant: “stronger” gene. Controls
what characteristic is expressed in a
person.
Recessive: “weaker” gene. If combined
with the dominant, characteristic will not
be expressed.
Sex is determined at conception by the X
and Y chromosome. Ovum carries the X
and the sperm carries either the X or Y.

6. Complete Heredity in the Works

7. TWINS!!!
Multiple births: woman gives birth to more than
one baby.
2 types of twins:
Identical: After conception, when cells begin to divide, if
the mass of cells splits in half, 2 separate cell masses
continue to grow into separate embryos.
Fraternal: form when 2 eggs are released and fertilized
by 2 different sperm. Common to be opposite sexes.
3% of all births are twins. Chances of having identical
are less than fraternal

8. Infertility
Infertility: the inability to become pregnant.
Male infertility is the problem about 40% of the time.
Female infertility is the problem about 40% of the time.
The rest is unknown.
 Female Infertility Video
 Male Infertility Video
 Infertility Solutions Video

9. Options for Infertility
1. Adoption
2. Artificial insemination: doctor injects sperm into a woman’s
uterus. Timed to take place when ovum is released.
3. In vitro fertilization: Doctor combines the ovum and sperm. If it
becomes fertilized, the doctor places it in the woman’s uterus.
Zygote then needs to attach to the uterus.
4. Ovum transfer: similar to in vitro, except ovum has been donated
by another woman.
5. Surrogate mother: substitute, mother is a woman who becomes
pregnant to have a baby for another woman. Requires legal
arrangements.

10. Miscarriage and Stillbirth
Miscarriage: if the death happens prior to the 20th
week
of pregnancy.
 About 15-20% of all recognized pregnancies end in miscarriage
Stillbirth: if the death happens after the 20th
week.
 Occurs in about 2% of pregnancies
Causes can be related to problems with the placenta,
abnormal chromosomes, poor growth, and infections.
Other causes are unknown.
Parents grieve the loss of an unborn baby similarly to
losing a child after it is born. They may need support to
work through their grief.

11. Birth Defects
Babies who are born with serious problems that
threaten their health and even their lives.
Some birth defects include:
Cerebral palsy
Cleft Lip and/or Cleft Palate
Cystic Fibrosis
Down Syndrome
Muscular Dystrophy
PKU
Sickle Cell Anemia
Spina Bifida and Hydrocephalus
Tay-Sachs Disease

12. Causes of Birth Defects
Environmental
Nutrition, disease or infection that mom has during
pregnancy, mom consuming harmful substances like
alcohol, drugs, certain medicines, exposure to
chemicals, X-rays.
Heredity Causes
Can occur with recessive inheritance (Tay-Sachs and
cystic fibrosis) or dominant inheritance (Huntington’s),
also some inherited conditions only affect one sex
(hemophilia, Duchenne Muscular Dystrophy, color
blindness only affects males.)

13. Other Causes of Birth Defects
Errors in Chromosomes
occurs when there are problems with the number or
structure of chromosomes. (Down syndrome-extra copy
of the 21st
chromosome).
Interaction of Heredity and Environment
Can be a combination of medicine mother is taking
(seizure and diabetes) and inherited genes. (cleft lip,
cleft palate, and spina bifida)

14. Prevention and Diagnosis
Mom and Dad need to take good care of
themselves if they are considering getting
pregnant.
Genetic Counseling: Evaluating the family
history of both parents and possibly doing blood
or tissue tests to determine chances of having
children with a birth defect.

15. Prenatal Tests
1. Alpha-fetoprotein (AFP) blood test performed
between 15-20 weeks of pregnancy. AFP is a
protein produced by the fetus’ liver that can be
detected in the mother’s blood
2. Ultrasound: uses sound waves to produce a
video image-sonogram.

16. More Pre-natal Tests
3. Amniocentesis: the process of withdrawing a
sample of the amniotic fluid surrounding the
unborn baby. Some cells from the fetus are in
the amniotic fluid. Usually only done after
previous tests show a possible problem.
4. Chorionic villi sampling: uses a sample of the
tissue from the membrane that encases the
fetus to check for specific birth defects

17. Avoiding Dangers to Baby
Alcohol
FAS-fetal alcohol syndrome: can have a wide
range of physical and mental disabilities that
last a lifetime-facial deformities, delayed
growth, heart defects, hyperactivity.
FAE-less severe than FAS, child suffers from
similar problems, but to a lesser degree.
Drugs-OTC (over the counter) and prescription
Some prescriptions are ok, but must be
monitored by a doctor

18. More Dangers To Baby
Caffeine
Large quantities can cause low birth weight
Tobacco
May cause low birth weight or even premature birth
Illegal Drugs
Can have devastating consequences:
Baby experiences withdrawal
Learning and behavioral problems
Can cause miscarriage, premature birth, or stillbirth
Can increase the risk of SIDS
Congenital heart disease

19. More Dangers
X Rays
The radiation can cause birth defects. If an X-Ray is
absolutely necessary, medical staff can take certain
precautions to make sure the fetus is not exposed to
much radiation.
Hazardous Substances
Paint, pesticides, lead, carbon monoxide, mercury,
solvents.
Infections
Rubella-most people today are vaccinated against
rubella. However, if expectant mom contracts rubella or
receives a vaccine for the illness, baby can have severe
birth defects.

20. More Dangers
 Toxoplasmosis
 Infection caused by a parasite. Doesn’t usually cause problems,
however developing babies are at risk if mom gets the disease. Can
cause blindness, hearing loss, or learning disabilities. Can be avoided
by not cleaning the cat’s litter box or eating undercooked meat.
 Chicken Pox
 If mom gets the chicken pox during the first half of pregnancy, a
condition can occur in which the baby may have scarring of the skin,
limb defects, eye problems or other abnormalities.
 STDs and AIDS
 STDs like syphilis, group B streptococcus, and gonorrhea can cause
problems for baby, such as blindness, serious illness, physical
disabilities, or even death.
 There is a 35-65% chance the AIDS virus will be passed from mom to
baby. AIDS attacks the brain leading to seizures and mental disabilities
in baby.