Please close this window when done.
| Age (years) | Frequency of
Fetuses with Down Syndrome to Normal Fetuses at 16 weeks of pregnancy |
Frequency of Live
Births of Babies with Down Syndrome to Normal Births |
|---|---|---|
|
15 - 19 |
---- |
1 / 1250 |
|
20 - 24 |
---- |
1 / 1400 |
|
25 - 29 |
---- |
1 / 1100 |
|
30 - 31 |
---- |
1 / 900 |
|
32 |
---- |
1 / 750 |
|
33 |
1 / 420 |
1 / 625 |
|
34 |
1 / 325 |
1 / 500 |
|
35 |
1 / 250 |
1 / 350 |
|
36 |
1 / 200 |
1 / 275 |
|
37 |
1 / 150 |
1 / 225 |
|
38 |
1 / 120 |
1 / 175 |
|
39 |
1 / 100 |
1 / 140 |
|
40 |
1 / 75 |
1 / 100 |
|
41 |
1 / 60 |
1 / 85 |
|
42 |
1 / 45 |
1 / 65 |
|
43 |
1 / 35 |
1 / 50 |
|
44 |
1 / 30 |
1 / 40 |
|
45 and older |
1 / 20 |
1 / 25 |
The zone written with yellow font is an increased risk zone while the zone written with red font is a high risk zone. The middle column above showing the occurrence rates at 16 weeks of pregnancy is mentioned because as per natural laws of survival of the fittest, many abnormal fetuses abort by this time.
Adapted from Hook EB. Journal of Am. Med. Assoc.; Vol. 249: Page 2034-2038, Year 1983.