Table 1. Sociodemographic and medical history of children and parents in ASD, ADHD and ASD-matched control study groups.

	ASD	ASD controls	ASD versus matched controls		ADHD	ADHD controls	ADHD versus matched controls
N=	1245	3405	Unadjusted	Model 1	1701	3797	Unadjusted	Model 1
			OR (95% CI)	OR (95% CI)			OR (95% CI)	OR (95% CI)
Child demographics
Age at first diagnosis, years (mean (s.d.))	5.5 (3.3)	—	—	—	8.8 (2.9)		—	—
Male gender	78.9%	79.6%	0.96 (0.82−1.12)	0.95 (0.79−1.14)	75.8%	79.6%	0.80 (0.70−0.92)*	0.76 (0.65−0.89)*
Race
White	65.2%	68.7%	0.85 (0.74−0.98)*	0.74 (0.57−0.97)*	73.4%	78.1%	0.77 (0.68−0.88)*	0.74 (0.57−0.95)*
Black	10.9%	9.0%	1.24 (1.00−1.53)*	1.53 (1.14−2.03)*	9.6%	7.2%	1.37 (1.11−1.67)*	1.51 (1.15−1.96)*
Hispanic	6.7%	5.8%	1.16 (0.88−1.50)	1.51 (1.05−2.16)*	6.6%	5.0%	1.33 (1.04−1.69)*	1.58 (1.15−2.17)*
Asian	7.3%	7.4%	0.97 (0.76−1.25)	1.21 (0.90−1.62)	1.9%	2.5%	0.76 (0.50−1.12)	0.74 (0.45−1.15)
Other	10.0%	9.0%	1.11 (0.89−1.38)	1.36 (1.04−1.77)*	8.5%	7.1%	1.21 (0.98−1.50)	1.36 (1.05−1.74)*
Median household income
First tertile (< $32,136)	29.3%	34.2%	0.80 (0.68−0.93)*	0.92 (0.74−1.14)	31.5%	33.7%	0.91 (0.79−1.04)	0.93 (0.77−1.12)
Second tertile ($32,136−$41,820)	38.3%	31.2%	1.37 (1.17−1.59)*	1.49 (1.22−1.82)*	37.4%	31.1%	1.33 (1.16−1.51)*	1.42 (1.19−1.69)*
Third tertile (> $41,820)	32.4%	34.5%	0.91 (0.78−1.06)	1.09 (0.88−1.35)	31.1%	35.2%	0.83 (0.72−0.95)*	1.08 (0.90−1.30)
Multiple birth	10.7%	8.4%	1.31 (1.05−1.62)*	1.28 (0.98−1.65)	6.9%	8.0%	0.85 (0.68−1.06)	0.96 (0.74−1.24)
Parent demographics
Mother age at delivery, years (mean (s.d.))	32.4 (5.4)	31.8 (5.6)	1.02 (1.01−1.03)*	1.04 (1.02−1.05)*	31.1 (6.2)	32.0 (5.4)	0.97 (0.96−0.98)*	0.99 (0.98−1.01)
Father age at delivery, years (mean (s.d.))	34.9 (6.5)	34.4 (6.2)	1.01 (1.00−1.02)*	1.00 (0.98−1.02)	33.3 (6.8)	34.4 (6.0)	0.97 (0.96−0.98)*	0.99 (0.97−1.00)
Mother−government insurance	16.3%	14.9%	1.11 (0.93−1.32)	1.20 (0.94−1.53)	18.6%	14.0%	1.41 (1.21−1.64)*	1.31 (1.06−1.62)*
Mother, 4+ years of college	63.7%	68.5%	0.81 (0.70−0.92)*	0.83 (0.69−1.01)	60.0%	69.7%	0.65 (0.58−0.73)*	0.82 (0.69−0.97)*
Father, 4+ years of college	64.8%	69.8%	0.80 (0.69−0.92)*	0.78 (0.64−0.94)*	58.4%	70.8%	0.58 (0.51−0.66)*	0.61 (0.52−0.72)*
Mother past medical history
Diabetes mellitus	4.1%	2.2%	1.91 (1.32−2.73)*	2.21 (1.45−3.35)*	3.6%	2.0%	1.82 (1.29−2.56)*	2.28 (1.53−3.38)*
Chronic hypertension	3.1%	2.1%	1.53 (1.02−2.26)*	1.17 (0.69−1.92)	2.9%	2.0%	1.52 (1.05−2.18)*	1.95 (1.29−2.92)*
Major depressive disorder	7.8%	7.7%	1.01 (0.79−1.29)	1.21 (0.87−1.66)	4.7%	4.8%	0.99 (0.75−1.29)	1.06 (0.75−1.49)
Parity
1	57.7%	52.6%	1.23 (1.08−1.41)*	1.30 (1.11−1.53)*	53.4%	52.4%	1.04 (0.92−1.17)	1.05 (0.92−1.21)
2	33.1%	34.8%	0.93 (0.81−1.07)	0.93 (0.79−1.09)	35.3%	34.9%	1.01 (0.90−1.15)	0.99 (0.85−1.14)
3+	9.2%	12.6%	0.70 (0.56−0.87)*	0.62 (0.48−0.80)*	11.4%	12.6%	0.89 (0.74−1.06)	0.91 (0.74−1.13)

Abbreviations: ASD, autism spectrum disorder; ADHD, attention-deficit hyperactivity disorder; CI, confidence interval; OR, odds ratio.

*Indicates uncorrected P<0.05.