Human Development I
Learning Objective and FCS
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
FCS Standards: FCS 5.A, 7.A, 7.D, 5.C
DNA: deoxyribonucleic acid.
Unique for each individual, unless you are a twin!
Genes: the units that determine a human’s
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.
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
Dominant and Recessive Genes
Dominant: “stronger” gene. Controls
what characteristic is expressed in a
Recessive: “weaker” gene. If combined
with the dominant, characteristic will not
Sex is determined at conception by the X
and Y chromosome. Ovum carries the X
and the sperm carries either the X or Y.
Multiple births: woman gives birth to more than
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
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
Options for Infertility
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
Miscarriage and Stillbirth
Miscarriage: if the death happens prior to the 20th
About 15-20% of all recognized pregnancies end in miscarriage
Stillbirth: if the death happens after the 20th
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.
Babies who are born with serious problems that
threaten their health and even their lives.
Some birth defects include:
Cleft Lip and/or Cleft Palate
Sickle Cell Anemia
Spina Bifida and Hydrocephalus
Causes of Birth Defects
Nutrition, disease or infection that mom has during
pregnancy, mom consuming harmful substances like
alcohol, drugs, certain medicines, exposure to
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.)
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
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)
Prevention and Diagnosis
Mom and Dad need to take good care of
themselves if they are considering getting
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.
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
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
Avoiding Dangers to Baby
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
More Dangers To Baby
Large quantities can cause low birth weight
May cause low birth weight or even premature birth
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
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
Paint, pesticides, lead, carbon monoxide, mercury,
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
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.
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