Updated January 16, 2005.

Question: Does my risk for having a baby with a birth defect increase as I get older?

Answer:

Women who are 35 years of age or older have a greater chance of having a baby with Down syndrome. Of the known causes of mental retardation, Down syndrome is the most common. It affects about 1 in 800 births. Down syndrome happens when there is an extra chromosome 21 ("trisomy 21"). Scientists have not proven that other birth defects, genetic or otherwise, are linked to the mother's age.

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