Table 1. Number of cases eligible for statistical analysis in each age group.
Age at the time of amnio-centesis | Total cases | Observed abnormal cases | Predicted rates (per 1,000 fetuses) | ||||
---|---|---|---|---|---|---|---|
T21 | T18 | T13 | Common autosomal trisomies | T21 | Common autosomal trisomies | ||
34 | 621 | 2 | 0 | 0 | 2 | 2.67 | 4.54 |
35 | 2,781 | 8 | 6 | 0 | 14 | 2.93 | 4.61 |
36 | 3,206 | 12 | 3 | 1 | 16 | 3.90 | 5.71 |
37 | 2,698 | 17 | 4 | 4 | 25 | 5.58 | 7.84 |
38 | 2,487 | 23 | 6 | 1 | 30 | 7.98 | 11.01 |
39 | 1,900 | 15 | 8 | 2 | 25 | 11.09 | 15.22 |
40 | 1,533 | 19 | 8 | 2 | 29 | 14.91 | 20.46 |
41 | 1,022 | 19 | 4 | 0 | 23 | 19.44 | 26.73 |
42 | 723 | 25 | 5 | 1 | 31 | 24.69 | 34.04 |
43 | 442 | 14 | 4 | 3 | 21 | 30.65 | 42.39 |
44 | 214 | 8 | 1 | 0 | 9 | 37.32 | 51.77 |
45 | 113 | 5 | 2 | 1 | 8 | 44.70 | 62.19 |
46 | 50 | 1 | 0 | 1 | 2 | 52.80 | 73.64 |
47 | 15 | 1 | 0 | 0 | 1 | 61.61 | 86.14 |
48 | 14 | 1 | 1 | 0 | 2 | 71.14 | 99.66 |
Total | 17,819 | 170 | 52 | 16 | 238 |
T21: trisomy 21, T18: trisomy 18, T13: trisomy 13.