Table 1.
General data of 2340 pregnant women
| Clinical features | Cases |
|---|---|
| Maternal age | |
| < 35 years | 2061 |
| ≥ 35 years | 279 |
| Gestation age at blood sampling | |
| 12-14 weeks | 80 |
| 15-20 weeks | 2239 |
| ≥ 24 weeks | 21 |
| Miscarriage history | |
| 0 time | 2172 |
| 1 time | 150 |
| 2 times | 14 |
| ≥3 times | 4 |
| Pregnant women(≥ 35 years) not screening for T21 | 147 |
| Down’s syndrome screening (high risk of T21) | 1189 |
| High risk of T18 | 18 |
| Only abnormal results of HCG marker | 558 |
| Only abnormal results of AFP marker | 319 |
| Only abnormal results of uE3 marker | 109 |
| Abnormal results of ultrasound (NT > 2.5 mm) | 72 |
HCG: Human Chorionic Gonadotropin; AFP: Alpha-fetoprotein; uE3: unconjugated estrio; NT: Nuchal Translucency.