Table 1.
Characteristics of women and chromosomal status of fetus/infant
| Characteristics | High risk (n = 1933) | Baseline risk (n = 1660) | |
|---|---|---|---|
| Age at edd | |||
| Mean (median) | 34.0 (34.0) | 32.9 (33.0) | |
| SD (range) | 5.4 (18–46) | 4.5 (19–53) | |
| Gestational age | |||
| Mean (median) | 17.1 (17.0) | 12.2 (12.3) | |
| SD (range) | 3.2 (10–23.9) | 1.0 (10–13.9) | |
| Weight (kg) | |||
| Mean (median) | 69.5 (65.8) | 67.1 (63.5) | |
| SD (range) | 14.9 (37–159) | 15.0 (40–167) | |
| Missing | 11 | 8 | |
| BMI, n (%) | |||
| <18.5 | 33 (1.7) | 74 (4.5) | |
| 18.5–24.9 | 971 (50.9) | 990 (60.2) | |
| ≥25.0 | 902 (47.3) | 582 (35.4) | |
| Missing | 27 | 14 | |
| Ethnicity (%) | |||
| Afro-Caribbean | 29 (1.5) | 39 (2.4) | |
| Asian | 155 (8.1) | 99 (6.0) | |
| European | 1491 (77.6) | 1272 (77.0) | |
| Oriental | 184 (9.6) | 188 (11.4) | |
| Other | 62 (3.2) | 54 (3.3) | |
| Missing | 12 | 8 | |
| Gravidity (%) | |||
| =1 | 482 (25.1) | 636 (38.6) | |
| >1 | 1437 (74.9) | 1012 (61.4) | |
| Missing | 14 | 12 | |
| Parity (%) | |||
| =0 | 751 (39.6) | 933 (56.4) | |
| =1 | 786 (41.4) | 553 (33.5) | |
| >1 | 360 (19.0) | 167 (10.1) | |
| Missing | 36 | 7 | |
| Smoking (%) | |||
| No | 1789 (92.8) | 1600 (97.2) | |
| Yes | 138 (7.2) | 47 (2.9) | |
| Missing | 6 | 13 | |
| Baby’s sex (%) | |||
| Female | 906 (46.9) | 789 (47.5) | |
| Male | 1027 (53.1) | 871 (52.5) | |
| Chromosomal status of fetus/infant (reference standard) | (% of 1933–% of 2163) | (% of 1660–% of 1759) | |
| Euploid sample removed randomly | 230 | 99 | |
| Euploid sample tested | 1651 (85.41) | 1648 (99.28) | |
| Trisomy 13 | 8 (0.41–0.37) | 0 (0–0) | |
| Trisomy 13—mosaic | 2 (0.10–0.09) | 0 (0–0) | |
| Trisomy 18 | 49 (2.53–2.27) | 0 (0–0) | |
| Trisomy 18—mosaic | 3 (0.16–0.14) | 0 (0–0) | |
| Trisomy 21 | 150 (7.76–6.93) | 5 (0.30–0.28) | |
| Trisomy 21—mosaic | 1 (0.05–0.05) | 0 (0–0) | |
| 45,X | 21 (1.09–0.97) | 1 (0.06–0.06) | |
| 45,X—mosaic | 1 (0.05–0.05) | 1 (0.06–0.06) | |
| 47,XXX or 47,XXY | 2 (0.10–0.09) | 0 (0–0) | |
| Triploidy | 10 (0.52–0.46) | 3 (0.18–0.17) | |
| Abn other | 35 (1.81–1.62) | 2 (0.12–0.11) | |