1. What is Down syndrome?
Down syndrome (DS) is a
chromosomal abnormality, also called trisomy 21, which affects about 1 in 800 live births. Patients with DS have an extra copy of part or all of chromosome 21. Most affected children have some retardation of growth and development. The risk of carrying a fetus with Down syndrome increases with the mothers age, especially in women over 40 years old. For more information, visit the
National Down Syndrome Society.
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2. What is a neural tube defect?
Neural tube defects are serious birth defects: the brain, spinal cord, or their coverings do not develop completely. There are 3 kinds of neural tube defects:
- Anencephaly: incomplete development of the brain and the skull.
- Encephalocele: a hole in the skull through which brain tissue protrudes.
- Spina bifida: the most common neural tube defect, in which the spine does not close properly during early pregnancy. (For more information on spina bifida, visit the Spina Bifida Association of America.)
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3. What is trisomy 18?
Trisomy 18 or Edwards Syndrome is a condition in which there are 3 copies of chromosome 18. The risk of carrying a fetus with trisomy 18 also increases with maternal age. Trisomy 18 is associated with multiple abnormalities and is usually fatal, with live-born infants rarely living beyond one year of age. The frequency of this abnormality is much less than Down syndrome, occurring in only 1 in 3000 live births. For more information, see the
Trisomy 18 Foundation website.
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4. What can I do to help prevent formation of a neural tube defect?
The U.S. Public Health Service recommends that all women of childbearing age should take 0.4 mg of folic acid daily.
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