Table 1 Demographic characteristics. Demographic characteristics of 101 pregnant women in Mirae & Heemang, Namujungwon, and GN hospitals in Korea

Maternal age, years, mean ± SD

35.55 ± 3.63

33.40 ± 3.64

35.45 ± 3.64

≥35 years (%)

59 (61.46)

1(20.00)

60 (59.41)

NIPT during gestational week 11–13 (%)

67 (69.79)

3 (60.0)

70 (69.31)

NIPT during gestational week 14–18 (%)

29 (30.21)

2 (40.0)

31 (30.69)

PGM, z-score of chr21 (min, max)

−3.46, 2.07

5.50, 9.43

<0.0001†

−3.46, 9.43

Proton, z-score of chr21 (min, max)

−2.32, 2.10

6.20, 8.86

<0.0001†

−2.32, 8.96