Transcript Birth Defects - Gladewater ISD

Birth Defects
By: Amanda
What causes birth defects?
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Genetic and environmental factors can cause birth defects.
A single abnormal gene can cause birth defects.
Every human has 20,000 to 25,000 genes that determine
traits like eye and hair color. Each child gets half its genes
from each parent. A person can inherit a genetic disease
when one parent, who may or may not have the disease,
passes along a single faulty gene, a dominant inheritance.
Each child gets half its genes from each parent. A person
can inherit a genetic disease when one parent (who may or
may not have the disease) passes along a single faulty
gene.
This is called dominant inheritance. Many other genetic
diseases are inherited only when both parents (who do not
have those diseases) happen to carry the same abnormal
gene and pass it on to a child. This is called a recessive
inheritance. (continued on next slide)
Examples of birth defects.
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Examples include achondroplasia (a form of
dwarfism) and Marfan syndrome (a
connective tissue disease).
Examples include Tay-Sachs disease (a fatal
disorder seen mainly in people of European
Jewish heritage) and cystic fibrosis (a fatal
disorder of lungs and other organs, affecting
mainly Caucasians).
There also is a form of inheritance (X-linked)
where sons can inherit a genetic disease
from a mother who carries the gene (usually
with no effect on her own health). Examples
include hemophilia (a blood-clotting disorder)
and Duchenne muscular dystrophy
(progressive muscle weakness).
More examples…
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Abnormalities in the number or structure of
chromosomes can cause numerous birth defects.
Due to an error that occurred when an egg or
sperm cell was developing, a baby can be born
with too many or too few chromosomes, or with
one or more chromosomes that are broken or
rearranged.
Down syndrome, in which a baby is born with an
extra chromosome 21, is one of the most
common chromosomal abnormalities. Affected
children have varying degrees of mental
retardation, characteristic facial features and,
often, heart defects and other problems.
Babies born with extra copies of chromosome 18
or 13 have multiple birth defects and usually die
in the first months of life.
Missing or extra sex chromosomes (X and Y)
affect sexual development and may cause
infertility, growth abnormalities, and behavioral
and learning problems.
What form do they take?
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Defects of limbs, heart and spinal cord represent about half of all
abnormalities.
The most common kinds of defect are those affecting the limbs (arms and
legs). These include missing or extra fingers or toes, deficiencies in limb
length, and abnormalities in positioning, such as club foot.
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Heart abnormalities represent the next most common category of defect.
Common heart defects include 'holes in the heart' where blood can pass from
one side of the heart to the other. Again, these may not all be detected at
birth.
The third most common kind of defect affects the spinal cord, such as spina
bifida.
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Other defects commonly observed include those affecting the face (such as
cleft lip and palate), problems with the development of the intestines and
stomach, and problems affecting the sexual organs.
Major chromosomal problems such as Down's syndrome (Trisomy 21) are
found in about 0.15 per cent of births (about three babies in every 2000).
What are the main environmental
factors causing birth defects?
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Thalidomide is perhaps the most notorious example of a drug
that caused defects.
It was brought on to the market after inadequate testing and
specifically prescribed for pregnant women. Following this,
much stricter rules about drug testing were introduced, and
international monitoring programmes were put in place.
Moderate alcohol use in pregnancy is a particularly tricky
problem. Many women who abuse alcohol may also have
unhealthy lifestyles - inadequate diet, smoking and lack of
exercise, and this confuses the issue in establishing the exact
role of alcohol.
Smoking is bad for the development of the baby in a number
of ways.
Environmental causes (including exposure to drugs, radiation
and illnesses) can be identified in about 10 per cent of birth
defects. The risk of exposure to such environmental factors
often causes great concern, although genetic causes are
more common.
(Continued on next slide)
Other factors
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The exact causes of the remaining 65 per cent of defects
are currently unclear. Many of these defects arise from
an interplay of genetic and environmental factors. For
instance, some babies may have a genetic susceptibility
to certain environmental factors.
If exposed to such factors during development, they
may develop an abnormality. If they are not exposed to
the factor, they will be perfectly normal.
Another baby exposed to the same environmental factor,
but who doesn't have the genetic susceptibility, may be
entirely normal. This can make it difficult to pin down
the exact cause of a defect.
Statistics.
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Every 8 seconds a baby is born in the United States. Every hour 3
babies die.
African American infants are more than twice as likely to die before
their first birthday as white infants.
Birth defects are the leading cause of infant mortality.
One in five infant deaths is due to birth defects.
Every 3 minutes a baby is born with a birth defect.
Every 2 minutes a low birth weight baby is born.
Every year nearly 3,900 babies are born weighing less than 1 pound at
birth.
Every minute a baby is born to a teen mother.
Each day 406 babies are born to mothers who received late or no
prenatal care.
More than 1 in 10 infants is born premature.
The US infant mortality rate is worse than 24 other nations.
What exactly is a birth defect?
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A birth defect is a problem that happens while the baby is developing
in the mother's body. Most birth defects happen during the first three
months of pregnancy.
A birth defect may affect how the body looks, works or both.
It can be found before birth, at birth or anytime after birth. Most defects
are found within the first year of life.
Some birth defects (such as cleft lip or clubfoot) are easy to see, but
others (such as heart defects or hearing loss) are found using special
tests (such as X-rays, CAT scans or hearing tests). Birth defects can
vary from mild to severe.
Some birth defects can cause the baby to die. Babies with birth defects
may need surgery or other medical treatments, but, if they receive the
help they need, these babies often lead full lives.
What are the most common among birth defects?
• One of every 33 babies is born with a birth defect. A birth defect can affect
almost any part of the body. The well-being of the child depends mostly on which
organ or body part is involved and how much it is affected.
• Many birth defects affect the heart. About 1 in every 100 to 200 babies is born
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with a heart defect.
Heart defects make up about one-third to one-fourth of all birth defects. Some of
these heart defects can be serious, and a few are very severe.
In some places of the world, heart defects cause half of all deaths from birth
defects in children less than one year of age.
• Other common birth defects are neural tube defects, which are defects of the
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spine (spina bifida) and brain (anencephaly).
They affect about 1 of 1,000 pregnancies. These defects can be serious and are
often life threatening. They happen less often than heart defects, but they cause
many fetal and infant deaths.
More common effects.
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Birth defects of the lip and roof of the mouth are also common. These birth defects,
known as orofacial clefts, include cleft lip, cleft palate and combined cleft lip and cleft
palate.
Cleft lip is more common than cleft palate. In many places of the world, orofacial
clefts affect about 1 in 700 to 1,000 babies.
These are only some of the most common birth defects. Two final points are worth
noting. First, genetic conditions, though not mentioned so far, also occur often.
Down's syndrome, for example, is a genetic condition that affects about 1 in 800
babies, but it affects many more babies who are born to older women.
Second, a woman who is pregnant may miscarry a baby early, before it is time for the
baby to be born. This often happens when the fetus has a severe birth defect.
All of the most common birth
defects.
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Anencephaly
A fatal birth defect that happens when the neural tube does not fully close at the top.
As a result, the skull and brain do not form properly. Babies with anencephaly die
before or shortly after birth.
Encephalocele
A birth defect that is often fatal. Part of a baby's skull does not form properly, and part
of the brain is outside of the skull. Those babies who do survive often have severe
physical and mental handicaps.
Neural tube
The tube along the back of an embryo which later becomes the spinal cord and brain.
Neural tube defect (NTD)
Problems in the growth of the spinal cord and brain in an embryo, when the neural
tube doesn't close at the top (anencephaly) or the bottom (spina bifida). The defects
occur in the first month of pregnancy, before most women know they are pregnant.
About seven babies are born in the U.S. each day with these birth defects.
Spina bifida
A birth defect of the backbone and spinal cord that leaves the spinal cord exposed. A
person with spina bifida may have learning disabilities or problems going to the
bathroom because of lack of bowel and bladder control, and usually needs crutches
or a wheelchair to get around. Eighty to ninety percent of babies with spina bifida
survive, and most lead productive lives.
Pictures.
anencephaly
Achondroplasia
Marfan syndrome
Tay-Sachs