Title: Can birth defects be treated before birth? Prenatal surgery
1Can birth defects be prevented?
How many babies in the United States are born
each year with birth defects?
Does moderate or light drinking during pregnancy
harm the baby?
Can birth defects be treated BEFORE BIRTH?
Acne Medicine?
Which EXTRA chromosome does a person with Down
Syndrome have?
When do chromosomal abnormalities usually occur?
body chemistry?
What is Achondroplasia?
What are TERATOGENS?
How many genes do each of us have?
CAN DIABETES AFFECT PREGNANCY?
What causes birth defects?
folic acid?
ULTRASOUND
What are the most common birth defects?
2FACTS
- About 120,000 babies (1 in 33) in the United
States are born each year with birth defects. - A birth defect is an abnormality of structure,
function or metabolism (body chemistry) present
at birth that results in physical or mental
disabilities or death. - Several thousand different birth defects have
been identified. - Birth defects are the leading cause of death in
the first year of life.
BACK
3What causes birth defects?
- Both genetic and environmental factors, or a
combination of these factors, can cause birth
defects. - However, the causes of about 70 percent of birth
defects are unknown.
BACK
4Single gene defects
- In many cases, a single gene change can cause
birth defects. - Every human being has about 20,000 to 25,000
genes that determine traits like eye and hair
color. - Genes also direct the growth and development of
every part of our physical and biochemical
systems. - Genes are packaged into each of the 46
chromosomes inside our cells.
BACK
5Single gene defects
- 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. Examples
include - Achondroplasia (a form of dwarfism)
- Marfan syndrome (a connective tissue disease)
BACK
6Single gene defects
- Many other genetic diseases are inherited when
both parents (who do not have the disease) carry
an abnormality in the same gene and pass it on to
a child. This is called recessive inheritance. - Examples include
- Tay-Sachs disease (a fatal nervous system
disorder) - Cystic fibrosis (a serious disorder of lungs and
other organs, affecting mainly Caucasians)
7Single gene defects
- There also is a form of inheritance called
X-linked, in which 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)
- Duchenne muscular dystrophy (progressive muscle
weakness)
8Chromosomal birth defects
- Abnormalities in the number or structure of
chromosomes can cause many birth defects. - Chromosomal abnormalities usually result from an
error that occurred when an egg or sperm cell was
developing. - As a result of this error, a baby can be born
with too many or too few chromosomes, or with one
or more chromosomes that are broken or
rearranged.
9Chromosomal birth defects
- Down syndrome, in which a baby is born with an
extra chromosome 21, is one of the most common
chromosomal abnormalities. - Children with Down syndrome 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 often die in
the first months of life. - Extra copies of most other chromosomes rarely
allow survival to live birth and are common
causes of miscarriage.
10Chromosomal birth defects
- Missing or extra sex chromosomes (X and Y) affect
sexual development and may cause infertility,
growth abnormalities and behavioral and learning
problems. - However, most affected individuals live fairly
normal lives. - Examples include
- Turner syndrome (in which a girl is missing all
or part of an X chromosome) and - Klinefelter syndrome (in which a boy has one or
more extra X chromosomes).
11Environmental factors
- Environmental substances that can cause birth
defects are called teratogens. - These include
- alcohol,
- certain drugs/medications,
- infections, and
- certain chemicals.
12Environmental factors
- Each year between 1,000 and 6,000 babies are born
with fetal alcohol syndrome (FAS) in this
country. - FAS is a pattern of mental and physical birth
defects that is common in babies of mothers who
drink heavily during pregnancy. - Women who are pregnant or planning pregnancy
should not drink any alcohol. - Even moderate or light drinking during pregnancy
may harm the baby.
13Environmental factors
- Some drugs and medications can contribute to
birth defects. - For example, the acne drug isotretinoin (sold
under the brand names Accutane, Amnesteem,
Claravis and Sotret) poses a high risk of serious
birth defects. A woman who is pregnant or who
could become pregnant should never use this drug.
- Illicit drugs such as cocaine also may pose a
risk.
14Environmental factors
- Certain infections can result in birth defects
when a woman contracts them during pregnancy. - About 40,000 babies a year (about 1 percent of
all newborns in this country) are born with a
viral infection called cytomegalovirus (CMV). A - About 1 in 10 infected babies develop serious
disabilities, including mental retardation and
loss of vision and hearing. - Pregnant women often get CMV from young children
who have few or no symptoms.
15Environmental factors
- Sexually transmitted infections in the mother
also can endanger the fetus and newborn. - For example, untreated syphilis can result in
stillbirth, newborn death or bone defects. - About 412 babies were affected by congenital
syphilis in 2002.
16Multi-factorial birth defects
- Some birth defects appear to be caused by a
combination of one or more genes and
environmental exposures. This is called
multi-factorial inheritance. - In some cases, an individual may inherit one or
more genes that make him more likely to have a
birth defect if he is exposed to certain
environmental substances (such as cigarette
smoke). - These individuals have a genetic predisposition
to a birth defect. - But if the individual is not exposed to the
environmental substance before birth, he probably
wont have the birth defect.
17Multi-factorial birth defects
- Examples of multi-factorial birth defects
include - Cleft lip/palate (opening in the lip and/or roof
of the mouth) - Neural tube defects (serious birth defects of the
brain and spinal cord, including spina bifida and
anencephaly) - Heart defects
18What are the most common birth defects?
- Cleft lip/palate and Down syndrome are among the
most common birth defects in the United States. - About 6,800 babies are born with cleft lip/palate
each year. Cleft lip/palate can cause problems
with eating, speech and language. - Some affected babies have a small cleft that can
be corrected with one surgical procedure, while
others have severe clefts and need multiple
surgeries. - About 5,500 babies are born each year with Down
syndrome.
19What are the most common birth defects?
- About 1,900 babies are born with a serious heart
defect called transposition of the great arteries
each year. - Many more babies are born with other serious
heart defects. While advances in surgery have
dramatically improved the outlook for affected
babies, heart defects remain the leading cause of
birth defect-related infant deaths. - Health care providers usually do not know what
causes a babys heart to form abnormally,
although both genetic and environmental factors
play a role. .
20What are the most common birth defects?
- Spina bifida (open spine) occurs in about 1,300
babies each year. - Affected babies have varying degrees of paralysis
and bladder and bowel problems. - Both genetic and environmental factors (including
insufficient amounts of a vitamin called folic
acid) appear to play a role.
21What are the most common birth defects?
- Other common birth defects include
musculoskeletal defects (including arm and leg
defects), gastrointestinal defects (including
defects of the esophagus, stomach and intestines)
and eye defects. - These birth defects usually are multi-factorial.
22What are birth defects of body chemistry?
- In 2002, about 3,000 babies were born with
disorders affecting body chemistry (metabolic
disorders). - These disorders are not visible, but they can be
harmful or even fatal.
23What are birth defects of body chemistry?
- Most disorders of body chemistry are recessive
genetic diseases. - These diseases result from the inability of cells
to produce enzymes (proteins) needed to change
certain chemicals into others, or to carry
substances from one place to another. An example
is - Tay-Sachs disease. Affected babies lack an
enzyme needed to break down certain fatty
substances in brain cells. These substances build
up and destroy brain cells, resulting in
blindness, paralysis and death by age 5.
24What are birth defects of body chemistry?
- Another example is phenylketonuria (PKU).
Affected babies cannot process a part of protein,
which builds up and damages the brain. - Newborn screening tests routinely detect babies
with PKU, so they can be placed on a special diet
that prevents mental retardation. - The March of Dimes recommends that all newborns
be screened for 29 disorders (including hearing
loss) for which effective treatment is available.
25Can birth defects be prevented?
- There are a number of steps a woman can take to
reduce her risk of having a baby with a birth
defect. - One important step is a preconception visit with
her health care provider. During this visit, the
provider can identify, and often treat, health
conditions that can pose a risk in pregnancy,
such as high blood pressure or diabetes. - The provider can provide advice on lifestyle
factors, such as quitting smoking and avoiding
alcohol, and occupational exposures that can pose
pregnancy risks. The provider also can make sure
that any medications a woman takes are safe
during pregnancy. - All of these steps help prevent birth defects.
26Can birth defects be prevented?
- A preconception visit is especially crucial for
women with chronic health conditions, like
diabetes, high blood pressure and epilepsy, which
can affect pregnancy. - For example, women with diabetes who have poor
blood sugar control are several times more likely
than women without diabetes to have a baby with a
serious birth defect. - However, if their blood sugar levels are well
controlled starting before pregnancy, they are
almost as likely to have a healthy baby as women
without diabetes.
27Can birth defects be prevented?
- At a preconception visit, the provider can check
to see if a womans vaccinations are up to date. - If she is not immune to rubella and chickenpox,
she should be vaccinated before pregnancy. - With widespread childhood vaccination, rubella is
now uncommon. However, if a pregnant woman comes
down with the disease, it poses a high risk of
birth defects. - Chickenpox also can cause birth defects, though
the risk is low. - A woman should wait for one month after being
vaccinated before trying to become pregnant.
28Can birth defects be prevented?
- The provider also will ask a woman about her
health history, as well as that of her partner
and her family. - This may help the provider identify risk factors
for birth defects or inherited genetic
conditions. - The provider may refer couples with risk factors
to a genetic counselor. - A genetic counselor can discuss the risks of
birth defects in their children and arrange for
blood tests (such as carrier tests), when needed.
29Can birth defects be prevented?
- All women who could become pregnant should take a
daily multivitamin containing 400 micrograms of
the B-vitamin folic acid. - Studies show that taking this vitamin before and
during early pregnancy reduces the risk of having
a baby with neural tube defects (spina bifida and
anencephaly). - If a woman already has had a pregnancy affected
by one of these birth defects, she should consult
her provider before pregnancy about how much
folic acid to take. - Generally a higher dose, 4 milligrams, is
recommended Women with diabetes or epilepsy or
who are obese are at increased risk of these
birth defects. They should ask their providers
before pregnancy about whether they should take
the larger dose of folic acid.
30Can birth defects be prevented?
- A woman who is pregnant or planning pregnancy
should avoid drinking alcohol, smoking and using
drugs. - All of these can cause birth defects and other
pregnancy complications. She should not take any
medication (prescription, over-the-counter or
herbal) without first checking with her health
care provider. - She should also avoid changing the cats litter
box or eating raw or undercooked meat. These are
possible sources of an infection called
toxoplasmosis that can cause birth defects.
31Can some birth defects be diagnosed before birth?
- Some birth defects can be diagnosed before birth
using one or more prenatal tests, including
ultrasound, amniocentesis and chorionic villus
sampling (CVS). - Ultrasound can help diagnose structural birth
defects, such as spina bifida, heart defects and
some urinary tract defects.
32Can some birth defects be diagnosed before birth?
- Amniocentesis and CVS are used to diagnose or
rule out chromosomal abnormalities, such as Down
syndrome, and numerous genetic birth defects. - Most women have screening tests (blood tests) to
see if they are at increased risk of certain
birth defects, including Down syndrome and spina
bifida. - These screening tests cannot diagnose a
condition, but they can suggest that further
diagnostic testing is needed.
33Can birth defects be treated before birth?
- A small percentage of couples learn through
prenatal diagnosis that their baby has a birth
defect. - While this news can be devastating, prenatal
diagnosis sometimes can improve the outlook for
the baby. - It is now possible to treat some birth defects
before birth. - For example,
- biotin dependence and methylmalonic academia (two
life-threatening inherited disorders of body
chemistry) have been diagnosed by amniocentesis
and treated in the womb, resulting in the births
of healthy babies.
34Can birth defects be treated before birth?
- Prenatal surgery has saved babies with urinary
tract blockages and rare tumors of the lung. More
than 300 babies have undergone experimental
prenatal surgery to repair spina bifida before
birth. Prenatal surgery poses a number of serious
risks for mother and baby, including preterm
birth. - (The National Institutes of Health is currently
conducting a study through 2007 to compare the
safety and effectiveness of surgery before and
after birth for babies with spina bifida. For
information contact http//www.spinabifidamoms.com
/.) - Doctors also have saved babies with serious heart
rhythm disturbances by treating the pregnant
woman with medications.
35Can birth defects be treated before birth?
- However, even when a fetus has a condition for
which prenatal treatment is not yet possible,
prenatal diagnosis permits parents to prepare
themselves emotionally, and to plan with their
provider the safest timing, hospital facility and
method of delivery. - Couples who have had a baby with a birth defect,
or who have a family history of birth defects,
should consider consulting a genetic counselor.
These health professionals help families
understand what is known about the causes of a
birth defect, and the chances of the birth defect
recurring in another pregnancy. - Genetic counselors can provide referrals to
medical experts as well as to appropriate support
groups in the community. The National Society of
Genetic Counselors provides the names and contact
information of genetic counselors.