Table 1 Demographic characteristics of the analytical sample (mother–child dyads)
From: Familial confounding in the associations between maternal health and autism
Variables | Diagnosed with autism (n = 18,374) | No autism diagnosis (n = 1,113,525) | Total (n = 1,131,899) |
|---|---|---|---|
Maternal age (years) at delivery, mean (s.d.) | 30.3 (5.1) | 30.6 (4.9) | 30.6 (4.9) |
Child’s sex, n (%) | |||
Female | 4,509 (24.5%) | 546,916 (49.1%) | 551,425 (48.7%) |
Male | 13,865 (75.5%) | 566,609 (50.9%) | 580,474 (51.3%) |
Child’s year of birth, n (%) | |||
1998 | 1,750 (9.5%) | 64,381 (5.8%) | 66,131 (5.8%) |
1999 | 1,875 (10.2%) | 64,365 (5.8%) | 66,240 (5.9%) |
2000 | 1,936 (10.5%) | 65,175 (5.9%) | 67,111 (5.9%) |
2001 | 1,754 (9.5%) | 63,695 (5.7%) | 65,449 (5.8%) |
2002 | 1,631 (8.9%) | 62,484 (5.6%) | 64,115 (5.7%) |
2003 | 1,526 (8.3%) | 63,133 (5.7%) | 64,659 (5.7%) |
2004 | 1,333 (7.3%) | 63,358 (5.7%) | 64,691 (5.7%) |
2005 | 1,237 (6.7%) | 63,123 (5.7%) | 64,360 (5.7%) |
2006 | 1,147 (6.2%) | 63,891 (5.7%) | 65,038 (5.7%) |
2007 | 1,010 (5.5%) | 63,200 (5.7%) | 64,210 (5.7%) |
2008 | 838 (4.6%) | 64,248 (5.8%) | 65,086 (5.8%) |
2009 | 732 (4.0%) | 62,203 (5.6%) | 62,935 (5.6%) |
2010 | 648 (3.5%) | 62,879 (5.6%) | 63,527 (5.6%) |
2011 | 460 (2.5%) | 58,662 (5.3%) | 59,122 (5.2%) |
2012 | 289 (1.6%) | 57,762 (5.2%) | 58,051 (5.1%) |
2013 | 142 (0.8%) | 55,814 (5.0%) | 55,956 (4.9%) |
2014 | 53 (0.3%) | 56,874 (5.1%) | 56,927 (5.0%) |
2015 | 13 (0.1%) | 58,278 (5.2%) | 58,291 (5.1%) |
Maternal income in DKK the year before delivery, mean (s.d.) | 203,452 (110,107) | 235,762 (214,650) | 235,237 (213,400) |
Missing, n (%) | 103 (0.6%) | 7,844 (0.7%) | 7,947 (0.7%) |
Paternal income in DKK the year before delivery, mean (s.d.) | 276,857 (196,233) | 316,626 (350731) | 315,980 (348,806) |
Missing, n (%) | 341 (1.9%) | 20,864 (1.9%) | 21,205 (1.9%) |
Maternal education the year before delivery, n (%) | |||
Primary or lower secondary level | 4,828 (26.3%) | 211,468 (19.0%) | 216,296 (19.1%) |
Upper secondary level and secondary vocational education | 7,844 (42.7%) | 447,248 (40.2%) | 455,092 (40.2%) |
Short-cycle tertiary, bachelor or equivalent | 3,865 (21.0%) | 292,433 (26.3%) | 296,298 (26.2%) |
Master, doctoral or equivalent | 1,217 (6.6%) | 106,567 (9.6%) | 107,784 (9.5%) |
Missing, n (%) | 620 (3.4%) | 55,809 (5.0%) | 56,429 (5.0%) |
Paternal education the year before delivery, n (%) | |||
Primary or lower secondary level | 4,828 (26.3%) | 211,468 (19.0%) | 216,296 (19.1%) |
Upper secondary level and secondary vocational education | 7,844 (42.7%) | 447,248 (40.2%) | 455,092 (40.2%) |
Short-cycle tertiary, bachelor or equivalent | 3,865 (21.0%) | 292,433 (26.3%) | 296,298 (26.2%) |
Master, doctoral or equivalent | 1,217 (6.6%) | 106,567 (9.6%) | 107,784 (9.5%) |
Missing, n (%) | 620 (3.4%) | 55,809 (5.0%) | 56,429 (5.0%) |
Number of days of maternal healthcare visits the year leading up to delivery, n (%) | |||
0 | 270 (1.5%) | 14,837 (1.3%) | 15,107 (1.3%) |
1–3 | 13,189 (71.8%) | 844,594 (75.8%) | 857,783 (75.8%) |
4–9 | 4,639 (25.2%) | 241,813 (21.7%) | 246,452 (21.8%) |
10+ | 276 (1.5%) | 12,281 (1.1%) | 12,557 (1.1%) |
Child’s parity, n (%) | |||
1 | 9,477 (51.6%) | 507,963 (45.6%) | 517,440 (45.7%) |
2–3 | 8,217 (44.7%) | 558,945 (50.2%) | 567,162 (50.1%) |
4–5 | 634 (3.5%) | 42,871 (3.9%) | 43,505 (3.8%) |
6+ | 46 (0.3%) | 3,746 (0.3%) | 3,792 (0.3%) |
Child has ID, n (%) | |||
No | 15,578 (84.8%) | 1,108,855 (99.6%) | 1,124,433 (99.3%) |
Yes | 2,796 (15.2%) | 4,670 (0.4%) | 7,466 (0.7%) |
Mother has at least two children in the cohort, n (%) | |||
No | 5,229 (28.5%) | 275,100 (24.7%) | 280,329 (24.8%) |
Yes | 13,145 (71.5%) | 838,425 (75.3%) | 851,570 (75.2%) |
