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.
| 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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