Characteristics of the cohort of liveborn, singleton infants born in English hospitals between 1 January 2003 and 1 January 2019, grouped by Down syndrome (DS) status
| Characteristics at birth | DS group | Non-DS group |
| n (%) | ||
| All | 10 621 (100%) | 96 210 125 (100%) |
| Sex | ||
| Male | 5460 (51%) | 4 745 180 (49%) |
| Female | 4532 (43%) | 4 514 788 (47%) |
| Missing | 629 (6%) | 361 057 (4%) |
| Ethnicity | ||
| White | 6623 (62%) | 6 188 957 (64%) |
| Asian or Asian British | 1203 (11%) | 918 876 (10%) |
| Black or black British | 855 (8%) | 446 473 (5%) |
| Mixed | 465 (4%) | 376 451 (4%) |
| Other | 305 (3%) | 222 940 (2%) |
| Missing or unknown | 1170 (11%) | 1 467 328 (15%) |
| Birth year | ||
| 2003–2006 | 2482 (23%) | 2 231 327 (23%) |
| 2007–2010 | 2651 (25%) | 2 462 815 (26%) |
| 2011–2014 | 2835 (27%) | 2 519 205 (26%) |
| 2015–2019 | 2653 (25%) | 2 407 678 (25%) |
| Birth weight | ||
| <1500 g | 299 (3%) | 63 562 (1%) |
| 1500–2499 g | 1857 (17%) | 404 174 (4%) |
| ≥2500 g | 6896 (65%) | 7 928 629 (82%) |
| Missing | 1569 (15%) | 1 224 660 (13%) |
| Gestational age | ||
| <32 weeks | 266 (3%) | 66 318 (1%) |
| 32–36 weeks | 1730 (16%) | 389 204 (4%) |
| ≥37 weeks | 6575 (62%) | 7 537 815 (78%) |
| Missing | 2050 (19%) | 1 627 688 (17%) |
| Maternal age | ||
| <20 years | 235 (2%) | 426 338 (4%) |
| 20–24 years | 792 (7%) | 1 471 724 (15%) |
| 25–29 years | 1220 (11%) | 2 275 341 (24%) |
| 30–34 years | 1997 (19%) | 2 447 449 (25%) |
| 35–39 years | 2752 (26%) | 1 353 956 (14%) |
| ≥40 years | 1939 (18%) | 308 693 (3%) |
| Missing | 1686 (16%) | 1 337 524 (14%) |
| Index of Multiple Deprivation Quintiles | ||
| Most deprived 20% | 3188 (30%) | 2 603 561 (27%) |
| Most deprived 20%–40% | 2368 (22%) | 2 069 232 (22%) |
| Middle 20% | 1823 (17%) | 1 720 027 (18%) |
| Least deprived 20%–40% | 1604 (15%) | 1 513 069 (16%) |
| Least deprived 20% | 1518 (14%) | 1 533 794 (16%) |
| Missing or unknown | 120 (1%) | 181 342 (2%) |