Table 1 Baseline characteristics of all individuals with intellectual disability and individuals without intellectual disability born in Denmark (1978–2016)
Characteristics | Individuals with ID, n (%) | Individuals without ID, n (%) |
|---|---|---|
Sex | ||
 Boys | 7434 (62.2) | 1,167,151 (51.3) |
 Girls | 4520 (37.8) | 1,109,288 (48.7) |
Preterm birth (< 37 gestational weeks) | ||
 Yes | 1197 (10.0) | 97,620 (4.3) |
 No | 10,315 (86.3) | 2,098,080 (92.2) |
 Missing | 442 (3.7) | 80,739 (3.5) |
Apgar score at 5Â min | ||
 10 | 10,138 (84.8) | 2,089,318 (91.8) |
  ≤ 9 | 1555 (13.0) | 149,585 (6.6) |
 Missing | 261 (2.2) | 37,536 (1.6) |
Parity | ||
 1 | 5000 (41.8) | 1,019,903 (44.8) |
 2 | 4148 (34.7) | 846,076 (37.2) |
  ≥ 3 | 2806 (23.5) | 410,460 (18.0) |
Maternal education level (years) | ||
  ≤ 9 | 6272 (52.5) | 597,386 (26.2) |
 10–15 | 4005 (33.5) | 974,963 (42.8) |
  ≥ 16 | 1395 (11.6) | 648,258 (28.5) |
 Missing | 282 (2.4) | 55,832 (2.5) |
Maternal age (years) | ||
  ≤ 24 | 3685 (30.8) | 460,732 (20.2) |
 25–29 | 4062 (34.0) | 832,359 (36.6) |
 30–34 | 2865 (24.0) | 677,836 (29.8) |
  ≥ 35 | 1342 (11.2) | 305,512 (13.4) |
Maternal original | ||
 Not born in Denmark | 1497 (12.5) | 260,364 (11.4) |
 Born in Denmark | 10,441 (87.4) | 2,009,997 (88.3) |
 Missing | 16 (0.1) | 6078 (0.3) |
Maternal psychiatric disorders | ||
 Yes | 1250 (10.5) | 160,848 (7.1) |
 No | 10,686 (89.5) | 2,112,473 (92.9) |
Age of the participants | ||
  ≤ 10 | 564,468 (25.8) | 678 (5.9) |
 11–19 | 597,087 (27.2) | 3390 (29.7) |
 20–29 | 585,249 (26.7) | 4591 (40.2) |
  ≥ 30 | 444,187 (20.3) | 2759 (24.2) |