Table 1. The baseline characteristics of the AMA women in present study.
| Characteristics | Number |
|---|---|
| Total | 4,224 |
| Ethnicity (Chinese) | 4,224 |
| Maternal age (years) | 36.87 (35.63–38.68) |
| Gestational age (weeks) | 20.30 (20.00–21.10) |
| Standard karyotype analysis | 3,475 (82.3%) |
| Standard karyotype analysis and CMA | 703 (16.6%) |
| CMA | 46 (1.1%) |
| Simple AMA | 3,748 (88.7%) |
| Maternal age (years) | 36.89 (35.64–38.68) |
| Gestational age (weeks) | 20.30 (20.00–21.10) |
| Standard karyotype analysis | 3,102 (82.8%) |
| Standard karyotype analysis and CMA | 607 (16.2%) |
| CMA | 39 (1.0%) |
| AMA combined with other indications | 476 (11.3%) |
| Maternal age (years) | 36.72 (35.61–38.61) |
| Gestational age (weeks) | 20.20 (19.50–21.00) |
| Ultrasonographic anomalies | 58 (12.2%) |
| History of adverse pregnancy | 119 (25.0%) |
| Spouse chromosome abnormalities | 54 (11.3%) |
| Assisted reproductive technology | 76 (16.0%) |
| High risk of prenatal screening | 103 (21.6%) |
| Twins | 62 (13.0%) |
| Others | 4 (0.8%) |
| Standard karyotype analysis | 373 (78.4%) |
| Standard karyotype analysis and CMA | 96 (20.2%) |
| CMA | 7 (1.5%) |
CMA, chromosomal microarray; AMA, advanced maternal age.