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Down Syndrome is a genetic disorder that means you have one extra chromosome, 47 instead of 46. It is typically diagnosed either prenatally or after birth. If you are receiving prenatal care, you will likely be offered genetic screening, which is done in the way of nuchal fold translucency testing or via AFP blood testing. If either of these tests are positive or indicate an increased risk of of risk, you may be offered or decide to do a genetic test called an amniocentesis or chorionic villus sampling (CVS) which can provide a definitive diagnosis of Down Syndrome.
Incidence of Down Syndrome with Increasing Maternal Age
Maternal Age at Delivery Risk at Term
32 1/725
33 1/592
34 1/465
35 1/365
36 1/287
37 1/255
38 1/177
39 1/139
40 1/109
41 1/85
42 1/67
43 1/53
44 1/41
45 1/32
46 1/25
47 1/20
48 1/16
49 1/12

OB/GYN Secrets
by Helen L. Frederickson, M.D. & Louise Wilkins-Haug, M.D. Ph.D.

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