Table 1 Characteristics of study population
Characteristic | Study population (n = 9452) |
|---|---|
Maternal age (years) | 31 (27–36) |
Advanced maternal age (≥ 35 yrs) | 3142 (33.2) |
Nation | |
Han | 6593 (69.8) |
Yi | 822 (8.7) |
Bai | 433 (4.6) |
Dai | 282 (3.0) |
Hui | 250 (2.6) |
Zhuang | 167 (1.8) |
Naxi | 145 (1.5) |
Hani | 112 (1.2) |
Others | 648 (6.8) |
Parity | |
Nulliparous | 3457 (36.6) |
Parous | 5995 (63.4) |
= 1 | 5355 (56.7) |
= 2 | 567 (6.0) |
≥ 3 | 64 (0.7) |
Gestational age at invasive diagnosis (weeks) | 20 (19–21) |
Invasive prenatal diagnosis procedure | |
Amniocentesis | 8855 (93.7) |
Cordocentesis | 552 (5.8) |
Chorion villus sampling | 44 (0.5) |
Maternal or/and paternal chromosome abnormalities | 155 (1.6) |
History of bearing child with chromosome abnormalities | 203 (2.1) |
Indications for invasive prenatal diagnosis | |
NIPT high-risk | 415 (4.4) |
Maternal serum screening high-risk | 1984 (21.0) |
DS high-risk | 2999 (31.7) |
ES high-risk | 799 (8.5) |
Both DS and ES high-risk | |
Advanced maternal age (≥ 35 yrs) | 1177 (12.5) |
Abnormal fetal ultrasonography | 1229 (13.0) |
Grade 1 | 1857 (19.6) |
Grade 2 | 1549 (16.4) |
Grade 3 | 531 (5.6) |
Grade 4 | 219 (2.3) |
Other indications | 831 (8.8) |
≥ two indications | 3816 (40.4) |