Table 2.

Crude and Adjusted Associations (Odds Ratios and 95% Confidence Intervals) Between Parental Age and Offspring ASD Diagnosis According to Continuous and Categorical Parental Age Parameterizations

	N	Crude	Adjusteda	Coadjustedb
Continuous models
Maternal age (10 year increase)	378	1.30 (0.73, 2.32)	1.46 (0.79, 2.72)	1.65 (0.73, 3.73)
Paternal age (10 year increase)	378	1.06 (0.66, 1.70)	1.10 (0.67, 1.77)	0.90 (0.47, 1.72)
Categorical models
Maternal age categories
<30	57 (12)	1.19 (0.54, 2.50)	1.03 (0.46, 2.22)	1.05 (0.45, 2.36)
30–34 (referent)	153 (12)	1.0 (referent)	1.0 (referent)	1.0 (referent)
≥35	168 (36)	1.22 (0.70, 2.13)	1.22 (0.69, 2.19)	1.20 (0.63, 2.30)
Paternal age categories
<30	41 (13)	2.84 (1.22, 6.54)	2.57 (1.06, 6.18)*	2.83 (1.14, 7.02)*
30–34 (referent)	121 (17)	1.0 (referent)	1.0 (referent)	1.0 (referent)
≥35 to <40	129 (25)	1.47 (0.76, 2.93)	1.46 (0.73, 2.96)	1.33 (0.65, 2.78)
≥40	87 (21)	1.95 (0.96, 4.00)	1.87 (0.91, 3.89)	1.50 (0.62, 3.63)
Combined effects
Young parents	25 (6)	1.36 (0.48, 3.39)	1.18 (0.40, 3.09)
Referent	281 (53)	1.0 (referent)	1.0 (referent)
Old parents	72 (17)	1.33 (0.70, 2.44)	1.29 (0.66, 2.41)

Note. Ns shown represent total n in analysis for continuous models, or n in that category for categorical models. Definitions as follows: young parents: both parents < 30 years; old parents: maternal age ≥ 35 and paternal age ≥ 40; referent combined effects category: all other combinations of parental age.

^aAdjusted for child’s sex, parental education, and parental race/ethnicity (maternal education and race/ethnicity used in maternal models; paternal education and race/ethnicity used in paternal age models).

^bAdditionally adjusted for the other parent’s age. Combined effects models adjusted for maternal race and education, though estimates adjusting for paternal race and education instead were similar.

^*Statistically significant (P < 0.05) in adjusted model.