Table 1 Demographic characteristics of the 59,800 pregnancies examined by NIPT.

Total

48,018(100.00%)

11,782 (100.00%)

Mean age when performed NIPT (SD), years

30.2 ± 12.5

30.1 ± 10.8

0.08

Gestational age at NIPT

 12 ~ 19^+ 6 weeks

27,975(58.26%)

9091(77.16%)

7.5549E-314

 20 ~ 23^+ 6 weeks

11,909(24.80%)

1332(11.31%)

2.2797E-219

 24 ~ 29^+ 6 weeks

6002(12.50%)

1141(9.68%)

3.08855E-17

 30 ~ 34^+ 6 weeks

2022(4.21%)

210(1.78%)

1.2109E-35

 ≥ 35 weeks

110(0.23%)

8(0.23%)

0.000411271

Serological screening for high or intermediate risks

22,160(46.15%)

6074(51.55%)

6.37874E-26

Serological screening for the single marker value abnormality(AFP, β-HCG, uE3)

14,790(30.80%)

1071(9.09%)

0

Ultrasound soft marker abnormalities

4634(9.65%)

2724(23.12%)

0

isolated advanced maternal age (≥ 35 years, AMA)

6170(12.85%)

1439(12.21%

0.06348737

Other types^a

264(0.55%)

474(4.03%)

1.2245E-205

IVF pregnancies

2900 (6.04%)

1120 (9.51%)

2.50238E-41

Fetal fragment fraction

15.78%(4.10-35.65%)

17.81%(7-36.807%)