Posts Tagged ‘Down Syndrome’

Birth defects

Friday, January 17th, 2014

In recognition of National Birth Defects Prevention Month, here are 10 things you need to know about birth defects from the Centers for Disease Control and Prevention, CDC.
 
1. Birth defects are common.
Birth defects affect 1 in 33 babies in the United States every year. For many babies born with a birth defect, there is no family history of the condition.

2. Birth defects are costly and can greatly affect the finances not only of the families involved, but of everyone.
In the United States, birth defects have accounted for over 139,000 hospital stays during a single year, resulting in $2.6 billion in hospital costs. Families and the government share the burden of these costs. Additional costs due to lost wages or occupational limitations can affect families as well.

3. Birth defects are critical conditions.
Birth defects can be very serious, even life-threatening.  About 1 in every 5 deaths of babies before their first birthday is caused by birth defects in the United States. Babies with birth defects who survive their first year of life can have lifelong challenges, such as problems with infections, physical movement, learning, and speech.

4. Women should take folic acid during their teens and throughout their lives to help prevent birth defects.
Because half of all pregnancies in the United States are not planned, all women who can become pregnant should get 400 micrograms of folic acid every day, either by taking a vitamin each day or eating a healthy diet. Folic acid helps a baby’s brain and spine develop very early in the first month of pregnancy when a woman might not know she is pregnant.

5. Many birth defects are diagnosed after a baby leaves the hospital.
Many birth defects are not found immediately at birth, but most are found within the first year of life. A birth defect can affect how the body looks, how it works, or both. Some birth defects like cleft lip or spina bifida are easy to see. Others, like heart defects, are found using special tests, such as x-rays or echocardiography.

6. Birth defects can be diagnosed before birth.
Tests like an ultrasound and amniocentesis can detect some birth defects such as spina bifida, heart defects, or Down syndrome before a baby is born. Prenatal care and screening are important because early diagnosis allows families to make decisions and plan for the future.

7. Birth defects can be caused by many different things, not just genetics.
Most birth defects are thought to be caused by a complex mix of factors. These factors include our genes, our behaviors, and things in the environment. For some birth defects, we know the cause. But for most, we don’t. Use of cigarettes, alcohol, and other drugs; taking certain medicines; and exposure to chemicals and infectious diseases during pregnancy have been linked to birth defects. Researchers are studying the role of these factors, as well as genetics, as causes of birth defects.

8. Some birth defects can be prevented.
A woman can take some important steps before and during pregnancy to help prevent birth defects. She can take folic acid; have regular medical checkups; make sure medical conditions, such as diabetes, are under control; have tests for infectious diseases and get necessary vaccinations; and not use cigarettes, alcohol, or other drugs.

9. There is no guaranteed safe amount of alcohol or safe time to drink during pregnancy.
Fetal alcohol spectrum disorders (FASDs) are a group of conditions that can occur in a person whose mother drank alcohol during pregnancy. These effects can include physical problems and problems with behavior and learning which can last a lifetime. There is no known safe amount, no safe time, and no safe type of alcohol to drink during pregnancy. FASDs are 100% preventable if a woman does not drink alcohol while pregnant.

10. An unborn child is not always protected from the outside world.
The placenta, which attaches a baby to the mother, is not a strong barrier. When a mother uses cigarettes, alcohol, or other drugs, or is exposed to infectious diseases, her baby is exposed also. Healthy habits like taking folic acid daily and eating nutritious foods can help ensure that a child has the best chance to be born healthy.
For more information: www.cdc.gov/birthdefects.

Written By: Cynthia A. Moore, M.D., Ph.D. Director
Division of Birth Defects and Developmental Disabilities
National Center on Birth Defects and Developmental Disabilities
Centers for Disease Control and Prevention

What causes Down syndrome?

Thursday, September 26th, 2013

Down syndrome is caused by extra genetic material from chromosome 21. Chromosomes are the structures in cells that contain the genes.

Each person normally has 23 pairs of chromosomes, or 46 in all. An individual inherits one chromosome per pair from the mother’s egg and one from the father’s sperm. When an egg and sperm join together, they normally form a fertilized egg with 46 chromosomes.

Sometimes something goes wrong before fertilization. A developing egg or sperm cell may divide incorrectly, sometimes causing an egg or sperm cell to have an extra chromosome number 21. When this cell joins with a normal egg or sperm cell, the resulting embryo has 47 chromosomes instead of 46. Down syndrome is called trisomy 21 because affected individuals have three number 21 chromosomes, instead of two. This type of error in cell division causes about 95 percent of the cases of Down syndrome.

Occasionally, before fertilization, a part of chromosome 21 breaks off during cell division and becomes attached to another chromosome in the egg or sperm cell. The resulting embryo may have what is called translocation Down syndrome. Affected individuals have two normal copies of chromosome 21, plus extra chromosome 21 material attached to another chromosome. This type of error in cell division causes about 3 to 4 percent of the cases of Down syndrome. In some cases, the parent has a rearrangement of chromosome 21, called a balanced translocation, which does not affect his or her health.

About 1 to 2 percent of individuals with Down syndrome have a form called mosaicism. In this form, the error in cell division occurs after fertilization. Affected individuals have some cells with an extra chromosome 21 and others with the normal number.

The risk of Down syndrome increases with the mother’s age. Even though the risk is greater as the mother’s age increases, about 80 percent of babies with Down syndrome are born to women under age 35. This is because younger women have more babies than older women.

To learn more about Down syndrome and the types of health problems someone with Down syndrome might have, read this article.

Chromosomal abnormalities

Tuesday, August 20th, 2013

chromosomes1About 1 in 150 babies in the US is born with a chromosomal condition. Babies with chromosomal conditions have a problem in one or more of their chromosomes. Chromosomes are the structures that hold genes. Genes are part of your body’s cells that store instructions for the way your body grows and works. Genes are passed from parents to children.

Each person has 23 pairs of chromosomes, 46 in all. For each pair, you get one chromosome from your mother and one chromosome from your father.

Chromosomal conditions are caused by two kinds of changes in chromosomes:
1. Changes in the number of chromosomes—This means there are too many or too few chromosomes.
2. Changes in the structure of chromosomes—This means that part of a chromosome may be missing, repeated or rearranged.

Chromosomal conditions usually result from an error that occurs when an egg or sperm cell develops. It is not known why these errors occur and as far as we know, nothing that a parent does or doesn’t do before or during pregnancy can cause a chromosomal abnormality in their child. In some cases these kinds of changes can be inherited or passed from parent to child.

In most cases, an embryo with the wrong number of chromosomes does not survive. In such cases, the pregnant woman has a miscarriage. This often happens very early in pregnancy, before a woman may realize she’s pregnant. More than 50 percent of first-trimester miscarriages are caused by chromosomal abnormalities in the embryo.

The American College of Obstetricians and Gynecologists recommends that all pregnant women be offered a screening test for Down syndrome and certain other chromosomal abnormalities. Screening may consist of a maternal blood test done in the first trimester (at 11 to 13 weeks of pregnancy) along with a special ultrasound of the back of the baby’s neck. It also can be a maternal blood test done in the second trimester (at 15 to 20 weeks). A screening test helps identify pregnancies that are at higher-than-average risk of these conditions.

However, a screening test cannot diagnose Down syndrome or other chromosomal abnormalities. If a screening test shows that your baby may have a problem, your provider gives you a diagnostic test that can tell you if your baby actually does or does not have a chromosomal condition. 

Diagnostic tests include amniocentesis or chorionic villus sampling. Your provider also can check your baby’s blood for chromosomal conditions after he’s born.

Each child born with a chromosomal condition is different. Some children with chromosomal conditions have intellectual disabilities or birth defects, or both. But some children with these conditions don’t have any serious problems. The problems depend on which chromosomes are affected and how they are affected.

If you or someone in your family has a chromosomal condition, or if you have a baby with a chromosomal condition, talk to a genetic counselor. A genetic counselor can help you understand the causes of chromosomal conditions, what kind of testing is available, and your chances of having a baby with these conditions.

What is a maternal-fetal medicine specialist?

Friday, March 15th, 2013

A maternal-fetal medicine specialist is an obstetrician who concentrates on the care of pregnant women and babies in high-risk situations. Another name for this doctor is a perinatologist.

A maternal-fetal medicine specialist treats women with a number of conditions. Complications with mom’s health, include:
• A history of multiple miscarriages or premature birth
• Diabetes (gestational or preexisting)
• Hypertension (high blood pressure)
• Preeclampsia
• Infectious disease (toxoplasmosis, parvovirus, HIV/AIDS, etc.) or chronic illness
• Rh disease
• A family history of heart, kidney, or other disease

A maternal-fetal medicine specialist often treat pregnant women who are carrying multiples (twins, triplets or more) as the risk for preterm birth is significantly increased.

This doctor also specializes in the care of women whose baby is known to have:
• Abnormal fetal growth
• A known birth defect or suspected genetic disorder, such as Down syndrome, Trisomy 13 or Trisomy 18
• A baby with macrosomia (too large)
• A baby with fetal growth restriction (too small)

If you find yourself in a position where the risk of complications is higher than the average pregnancy, ask your current health care provider for a referral to a maternal-fetal medicine specialist. You may or may not need the extra care, but it will be good to get a second opinion.

New prenatal blood test

Thursday, December 13th, 2012

New prenatal tests can give some parents piece of mind that the baby they’re expecting doesn’t have a disorder.  The tests are given sooner and with greater accuracy and less risk of miscarriage than current tests.

The new tests, which use fetal DNA suspended in the mother’s blood, can test for chromosomal disorders such as Down syndrome (trisomy 21) and trisomy 18, and Rh blood incompatibility. They also can determine the baby’s gender, which allows health care providers to screen for disorders such as hemophilia.

During pregnancy, fetal cells and cell-free fetal genetic material circulate in the mother’s bloodstream.  This DNA can be used to screen for certain genetic disorders without having to perform invasive procedures such as amniocentesis or CVS (chorionic villus sampling).

At present four widely used procedures assist health care providers in prenatal diagnosis. They are:
   • Amniocentesis: a procedure that collects some of the amniotic fluid that surrounds the fetus for analysis. This is a diagnostic test.  
   • Chorionic villus sampling (CVS): a procedure that obtains tissue from around the placenta. This is a diagnostic test.  
   • Maternal blood tests: screening tests that use mother’s blood to help identify problems with the fetal brain, spinal cord, intestines or chromosomes. These tests include alpha-fetoprotein (AFP), hCG and other hormones. As with all forms of screening, abnormal results require follow-up testing to make a diagnosis.
   • Ultrasound: a scan using sound waves to visualize the fetus. 

Cell-free DNA methods of screening are a new option. “Prenatal diagnosis gives parents important information about the health of their baby and the status of their pregnancy. More often than not, prenatal screening reassures parents that their baby is healthy and that these disorders are not present,” says Joe Leigh Simpson, MD, March of Dimes senior vice president for Research and Global Programs.  “For a high-risk infant, prenatal diagnosis gives parents and health care providers options that may include planning for a health problem or arranging for delivery in a medically appropriate setting. The first step toward treating these problems is diagnosing them, and cell-free DNA methods, without the need for invasive measures, are welcomed.”

Dr. Lee P. Shulman of Northwestern University says, “while this represents a profound improvement in our ability to identify women at increased risk for carrying fetuses with the most common chromosome abnormalities, still, this technology represents a limited screening protocol and should not serve as a substitute for diagnostic tests such as chorionic villus sampling and amniocentesis, which provide the most accurate and comprehensive assessment by the direct analysis of fetal tissue.”

The American College of Obstetricians and Gynecologists and the American College of Medical Genetics recommend that information on prenatal genetic screening and diagnosis should be made available to all pregnant women and those considering pregnancy.

With all the above options for testing available, it’s important to discuss what is best for you and your pregnancy with your health care provider.

Blood test vs. amniocentesis

Thursday, January 13th, 2011

blood-testsResearchers are working on a new blood test that has the potential to diagnose Down syndrome in women who are at high risk for having a baby with this condition. If proven successful, this test might eliminate the need for the more invasive and risk-related tests of amniocentesis and chorionic villus sampling (CVS).  Both amniocentesis and CVS carry a risk of miscarriage

A study conducted at the Chinese University of Hong Kong and recently published in the British Medical Journal (BMJ), included 753 pregnant women. Of these, 86 women were carrying a fetus with Down syndrome. There were no false-negative results with the new test. All babies with Down syndrome were detected. The study authors state that “If referrals for amniocentesis or chorionic villus sampling were based on the sequencing test results, about 98% of the invasive diagnostic procedures could be avoided. “

Further evaluation of this technology needs to be conducted before it is offered to the public, but this is exciting and hopeful science.  While the test won’t be available for at least another year, and the cost may be high, and currently it tests only for Down syndrome and not other conditions, it holds promise for the future.  It will be a new and safe screening tool to help us gather information about our developing babies.

Do those blood tests confuse you?

Monday, August 9th, 2010

For those of you who are pregnant, sometime between 15-20 weeks of pregnancy, you will be offered maternal serum screening.  What is this?  And more importantly, what do the results mean?  I think maternal blood screening is one of the most misunderstood tests in pregnancy.  And for some women it can be a very nerve-wracking experience. 

The American College of Obstetricians and Gynecologists (ACOG) recommends that all pregnant women regardless of age be offered a screening test for Down syndrome and certain other birth defects.  This is a blood test that looks at the levels of either 3 or 4 (depending on the test) chemicals that are present in a pregnant woman’s blood.  The chemicals are AFP (alpha fetoprotein), hCG (human chorionic gonadotropin—the same chemical that a home pregnancy test measures), estriol, and recently most labs have added a fourth substance, inhibin A.  These chemicals are present in every pregnant woman’s blood.  Some of them are produced by the fetus while others are hormones produced by the placenta. 

Maternal serum tests such as the triple screen or the quad screen as they are commonly called, look at the levels of these 3 or 4 chemicals in the mother’s blood and the woman’s age, weight, race, number of fetuses (e.g. twins) and whether she has diabetes that requires insulin treatment.  Then given all of those factors and the levels of the 3 or 4 chemicals the laboratory can determine the chance that a woman has a baby with Down syndrome, a neural tube defect (spina bifida), trisomy 18, or abdominal wall defects.

There are two different ways that the results may be reported.  A woman may receive her test result as a ratio. For example, her baby has a 1 in 500 chance for Down syndrome. Or, in some cases, a woman’s test results are reported as normal (screen negative) or abnormal (screen positive), depending on whether her results fall below or above a cut-off point (usually about 1 in 270).

The test is NOT a diagnosis of any of these conditions though.  This is where there is a lot of confusion.  By definition, screening tests do not diagnose a condition.  They only determine whether there is an increased risk for the condition.  The good news is that of all of the women who screen positive, only a small percentage will actually have a baby with one of these disorders.  Many times women have an abnormal result simply because their fetus is a few weeks older or younger than previously thought.  

For women with abnormal results, the next step is usually an ultrasound. This test can check the gestational age of the fetus and show if a woman is carrying multiples. If either of these factors accounts for the abnormal test result, no further testing is needed. If ultrasound does not explain the abnormal test result, amniocentesis will be offered.  An amniocentesis is an invasive test where the doctor uses a needle to remove some of the amniotic fluid around the baby.  Although amnio does pose a very slight risk of miscarriage (1/4 of one percent or 1/500), it is extremely accurate and usually can give a pregnant woman a definitive answer.  Should a problem exist, arrangements can be made in advance for special care of the newborn at delivery.

Screening for birth defects

Tuesday, September 9th, 2008

At my last prenatal appointment I had a combination of tests done to screen for birth   defects such as Down syndrome and Trisomy 13 and 18. I was nervous going, but my husband was with me for support. My visit started with an ultrasound. The doctor rubbed a hand-held device (called a transducer) across my belly. The baby was face up and the doctor needed him/her to turn to the side in order to measure the thickness at the back of the neck (called nuchal translucency).  We waited and waited, but he/she wouldn’t budge. I certainly didn’t mind because I was able to admire the beautiful image on the screen longer.

After several minutes, the doctor finally called for a nurse. She brought me a very sweet orange drink and the doctor said he would be back in less than 10 minutes. I was thinking, “yeah right, this isn’t going to work.” Well, wouldn’t you know it. When he came back and put the transducer on my belly, there it was — the most perfect profile. I guess the baby just needed a little energy. Using the mouse on the ultrasound machine, he was able to measure the back of the neck.

Then I was passed off to the nurse who took a blood sample. I don’t know if this is always the case with maternal blood screening, but she pricked my finger and placed about 5 or 6 drops of blood on a card. The office sent the blood sample to a lab and I would get the results back in about four days. The lab calculated my risk of chromosomal birth defects, using the combined results of my blood test and ultrasound exam.

I received a call a few days later. I was told that based on my age, blood work and ultrasound my risk for Down syndrome was 1 in 1, 610 and my risk for Trisomy 18/13 was 1 in > 10,000. I know that no test can gaurantee the birth of a healthy baby, but I was so relieved. It’s always nice to here reassuring news. Waiting for test results can be so stressful.