Table 1. Clinical characteristics of study subjects.
| Clinical characteristics | Data | |
|---|---|---|
| Maternal age, yr | 36 (22–48) | |
| < 35 | 342 (32.4) | |
| ≥ 35 | 713 (67.6) | |
| Gestational age, wk | 16.1 (10–21.4) | |
| 1st trimester | 462 (43.8) | |
| 2nd trimester | 593 (56.2) | |
| Body mass index, kg/m2 | 21.4 (14.9–53.5) | |
| Gender-ratio of fetus (men:women) | 550:505 (52:48) | |
| Indication for karyotyping | ||
| Advanced maternal age | 442 (41.8) | |
| Ultrasound abnormality | 181 (17.1) | |
| Positive serum screening | 128 (12.1) | |
| Multiple indication | 266 (25.2) | |
| Others | 38 (3.6) | |
| Chromosomal karyotype | 1,055 (100) | |
| Normal | 947 (89.8) | |
| Trisomy 13 | 9 (0.8) | |
| Trisomy 18 | 42 (4.0) | |
| Trisomy 21 | 57 (5.4) | |
Values are median (range) or number (%).