Table 1 Demographics and specimen types in cases with common aneuploidies for chromosomes 21, 18, and 13 and RAAs

Maternal age (years)

34 (28–39)

32 (28–37)

p < 0.05

 ≥ 35 years old

954 (49.48%)

35 (38.89%)

0.052

Gestational ages (weeks)

18 (17–19)

18 (16–20)

0.568

Specimen types

 Chorionic villus

301 (15.61%)

17 (18.89%)

–

 Amniotic fluid

1532 (79.46%)

71 (78.89%)

–

 Cord blood

95 (4.93%)

2 (2.22%)

–

Classification

 Mosaic trisomies

69 (3.58%)

83 (92.22%)

p < 0.001