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Table 1 Demographic characteristics of women requesting cell-free DNA (cfDNA) screening for common trisomies and sex chromosome aneuploidies

From: Performance of cell-free DNA sequencing-based non-invasive prenatal testing: experience on 36,456 singleton and multiple pregnancies

Characteristics n (%) unless otherwise stated
Low risk NIPT results 35,955 (98.6)
Singleton pregnancies (%) 35,650 (97.8)
Twin pregnancies (%) 800 (2.2)
Triplet pregnancies,(%) 6 (0.02)
ART Pregnancies(%) 1807 (5)
 Twin pregnancies (%) 403 (22.3)
 Egg donation (%) 16 (0.9)
Maternal age (yrs) mean (range)* 35.4 (18–48)
 < 35(%) 19,693 (54)
 ≥ 35(%) 16,763 (46)
Gestational age (wks + days) mean (range) 12 + 2 (9 + 1–32 + 6)
Samples drawn in first trimester (< 13 + 6 wks) 27,780 (76.2%)
Fetal fraction mean ± SD 9.55 ± 3.72
Fetal fraction first trimester mean ± SD 9.53 ± 3.69
  1. ART artificial reproductive technology
  2. *We excluded pregnancies with egg donation