Down Syndrome and Your Unborn Baby

What is Down syndrome?

Down syndrome is a genetic disorder that causes mental retardation and physical defects. It is caused by the presence of an extra copy of chromosome number 21. This condition is called trisomy 21.

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What are the health problems that might affect a baby who has Down syndrome?

Down syndrome usually causes mild to moderate mental retardation, or slow mental growth. Language skills develop slowly in babies who have Down syndrome. About half of babies who have Down syndrome are also born with heart problems, some of which may require surgery. Some babies who have Down syndrome also have intestinal problems, thyroid disease, vision trouble or hearing loss. Many of these problems can be treated with medical attention and educational assistance as the baby gets older.

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Are some people more likely than others to have a baby who has Down syndrome?

If you have already had a baby who has Down syndrome, you are more likely to have another one. For every 100 couples who has another baby, 1 will have another who has Down syndrome. If you have been diagnosed with a chromosomal abnormality, you also have an increased risk of having a baby who has Down syndrome.

Additionally, the risk of Down syndrome increases with the age of the mother, as shown in this table:

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Risk of Down Syndrome

Mother's age	Chance of having a baby with Down syndrome
20 years	1 in 1,667
25 years	1 in 1,300
30 years	1 in 950
35 years	1 in 365
40 years	1 in 100
45 years	1 in 30

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Can Down syndrome be diagnosed during my pregnancy?

Amniocentesis and chorionic villus sampling are two tests that can be used to look for Down syndrome during the first half of your pregnancy. However, there is a slight risk that these tests can cause a miscarriage. Therefore, these tests are used only when there is a high chance of a genetic problem in the baby (such as a mother age 35 or older).

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Is there another way to tell if my baby might have Down syndrome?

A blood test called the "quad marker screen" can be done between the 15th and the 22nd weeks of pregnancy, but it's more accurate when done between the 16th and 18th weeks. The quad marker screen cannot tell for sure if your baby has Down syndrome or other chromosomal disorders, but it can tell if the risk is higher. If the test is positive, it means your risk of having a baby who has Down syndrome is higher. But remember that many women with a positive quad marker screen have babies that do not have Down syndrome.

A negative triple screen means that the chance of Down syndrome is low. However, it doesn't guarantee that a baby doesn't have Down syndrome.

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Should I be tested?

This decision is up to you. Some women feel better if they know if their baby is at risk so that they can prepare themselves for the possibility of having a baby who has Down syndrome. Your doctor can help you understand your risks and consider the pros and cons of getting tested.

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Other Organizations

National Down Syndrome Congress
7000 Peachtree-Dunwoody Rd. NE, Bldg. 5, Suite 100
Atlanta, GA 30328-1662
800-232-6372
National Down Syndrome Society
666 Broadway
New York, NY 10012
800-221-4602
National Institute of Child Health and Human Development
PO Box 3006
Rockville, MD 20847
800-370-2943
March of Dimes
1275 Mamaroneck Ave.
White Plains, NY 10605
888-MODIMES (663-4637)