Table 3.
Chromosomal abnormalities according to maternal ages
| Maternal age (years) | No. of births | No. of abnormal cases (per 10,000 births) | T21 | T18 | T13 | Sex-related | Structural abnormality |
|---|---|---|---|---|---|---|---|
| <20 | 37,539 | 3(0.80) | 3(0.80) | 0 | 0 | 0 | 0 |
| 21 ~ 24 | 296,130 | 98(3.31) | 87(2.94) | 5(0.17) | 0 | 5(0.17) | 1(0.03) |
| 25 ~ 29 | 553,822 | 209(3.78) | 174(3.14) | 19(0.34) | 1(0.02) | 12(0.22) | 3(0.11) |
| 30 ~ 34 | 268,036 | 214(7.98) | 179(6.68) | 13(0.49) | 3(0.11) | 15(0.56) | 4(0.15) |
| 35 ~ 47 | 114,824 | 287(24.99) | 246(21.42) | 16(1.39) | 3(0.26) | 16(1.39) | 6(0.52) |
| Total | 1,270,351 | 811(6.38) | 689(5.42) | 53(0.42) | 7(0.06) | 48(0.38) | 14(0.11) |