Table 2 Relative risk for ASD and AD, with associated two-sided 95% confidence intervals by maternal and parental age

From: Autism risk associated with parental age and with increasing difference in age between the parents

Outcome

Age interval a

Maternal age crude

Maternal age adjusted b

Paternal age crude

Paternal age adjusted b

ASD

<20/20–29

1.16 (1.07–1.26)

1.18 (1.08–1.29)

1.23 (1.05–1.43)

1.08 (0.92–1.27)

 

30–39/20–29

1.02 (0.99–1.04)

0.98 (0.95–1.01)

1.01 (0.99–1.04)

1.05 (1.02–1.08)

 

40–49/20–29c

1.34 (1.24–1.44)

1.15 (1.06–1.24)

1.27 (1.22–1.32)

1.28 (1.22–1.34)

 

⩾ 50/20–29

  

1.64 (1.47–1.82)

1.66 (1.49–1.85)

AD

<20/20–29

1.11 (0.96–1.27)

1.17 (1.01–1.36)

1.15 (0.88–1.51)

1.05 (0.78–1.40)

 

30–39/20–29

1.11 (1.07–1.16)

0.96 (0.91–1.01)

1.13 (1.08–1.18)

1.11 (1.06–1.17)

 

40–49/20–29c

1.60 (1.43–1.78)

1.15 (1.01–1.29)

1.57 (1.47–1.67)

1.52 (1.40–1.64)

 

⩾ 50/20–29

  

2.18 (1.87–2.54)

2.05 (1.75–2.41)

  1. Abbreviations: AD, autistic disorder; ASD, autism spectrum disorder.
  2. aRelative risks compared with 20–29 year
  3. bAdjusted for site, sex, birth year (4-year-intervals), age of the other parent (mother: <20, 20–29, 30–39 and ⩾40 years; father: <20, 20–29, 30–39, 40–49 and ⩾50 years), sex (male/female), birth year (4-year intervals) and site (Denmark, Israel, Norway, Sweden, Western Australia).
  4. cFor maternal age this is 40–49 is⩾40 year.
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