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An article on this topic is available in this issue of AFP.
Down Syndrome: What You Need to Know When You're Pregnant
What is Down syndrome?
Down syndrome is one of the most common genetic disorders. It's caused by the presence of an extra copy of chromosome number 21. This condition is called trisomy 21.
What problems do babies with Down syndrome have?
Down syndrome usually causes mild to moderate mental retardation, or slow mental growth. Almost half of babies with Down syndrome are born with heart problems. Some of these problems can only be fixed with surgery. Some babies with Down syndrome have intestinal problems, vision trouble or hearing loss. Many of these problems can be treated.
Are some people more likely than others to have a baby with Down syndrome?
If you have already had a baby with Down syndrome, you are more likely to have another one. If you have been diagnosed with a chromosome abnormality, you have an increased risk of having a baby with Down syndrome.
The risk of Down syndrome increases with the age of the mother, as shown in this table:
Risk of Down Syndrome Mother's age Chance of having a baby with Down syndrome 20 years 1 in 1,600 25 years 1 in 1,300 30 years 1 in 1,000 35 years 1 in 365 40 years 1 in 90 45 years 1 in 30 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, these tests can sometimes cause a miscarriage. Therefore, these tests are used only when there is a high chance of a genetic problem in the baby.
Is there another way to tell if my baby might have Down syndrome?
A blood test called the "triple screen" can be done between the 15th and the 18th weeks of pregnancy. The triple screen cannot tell for sure if your baby has Down syndrome, but it can tell if the risk is higher. If the test is positive, it means your risk of having a baby with Down syndrome is higher. But remember that most women with a positive triple screen have babies without Down syndrome.
A negative triple screen means that the chance of Down syndrome is low. However, it doesn't guarantee a baby without Down syndrome.
Sources for Information About Down Syndrome You can call or write to the following organizations for more information: March of Dimes Birth Defects Foundation
1275 Mamaroneck Ave.
White Plains, NY 10605
1-888-MODIMES (663-4637)
Web address: http://www.modimes.orgNational Down Syndrome Society
666 Broadway St.
New York, NY 10012
1-800-221-4602; 212-460-9330
Web address: http://www.ndss.orgNational Institute of Child Health and Human Development
NICHD Clearinghouse
PO Box 3006
Rockville, MD 20847
1-800-370-2943
Web address: http://www.nichd.nih.gov
Ask for the brochure, "Facts about Down Syndrome" (available in English and Spanish).National Down Syndrome Congress
7000 Peachtree-Dunwoody Rd. NE, Bldg. 5, Suite 100
Atlanta, GA 30328-1662
1-800-232-6372; 770-604-9500
Web address: http://www.ndsccenter.org
This handout provides a general overview on this topic and may not apply to everyone. To find out if this handout applies to you and to get more information on this subject, talk to your family doctor.
Visit familydoctor.org for information on this and many other health-related topics.
Copyright © 2000 by the American Academy of Family Physicians.
Permission is granted to print and photocopy this material for nonprofit educational uses. Written permission is required for all other uses, including electronic uses.
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