We tabulated associated birth defects seen in 2894 infants with Down syndrome and found:
|Heart defects are the most frequent associated defect, affecting 56% of cases. The most common type is atrioventricular canal/endocardial cushion defects, seen in 17% of cases—1000 times more frequently than in babies without Down syndrome.|
|About 11% have defects of the gastrointestinal tract. Duodenal atresia—found in about 5%— is 265 times more common in babies with Down syndrome than in the general population.|
|There is substantial overlap between heart and gastrointestinal defects. For example, 86% of infants with duodenal atresia also have heart defects.|
RISK FACTORS FOR ASSOCIATED DEFECTS
Serious structural birth defects occur in many but not all infants with Down syndrome. Do environmental factors-interacting with the developmental instability caused by the extra chromosome-influence which babies have associated abnormalities? We interviewed mothers of 687 infants with Down syndrome to answer this question for heart and gastrointestinal defects.
|4.2% of these mothers drank 4 or more cups of coffee daily; they had a 6 times higher chance of having a baby with Hirschsprung disease.|
|12% of mothers smoked during the first trimester. Their babies had double the risk for heart defects compared to babies of nonsmokers.|
|Several factors were not associated with any Down syndrome-associated defect: – Fever – Alcohol use
– Mother’s age.
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