Table 1.

Study population characteristics by autism spectrum disorder status and population controls in the Central Valley, CA*

	ASD (all; n=2961)	ASD with ID (n=445)	ASD without ID (n=2516)	Controls (n=35 370)
					Sex
Males	2403 (81.2)	354 (79.6)	2049 (81.4)	29 225 (82.6)
Females	558 (18.8)	91 (20.4)	467 (18.6)	6145 (17.4)
Year of birth
1998-2004	1033 (34.9)	243 (54.6)	790 (31.4)	14 390 (40.7)
2005-2010	1928 (65.1)	202 (45.4)	1726 (68.6)	20 980 (59.3)
Maternal age
≤19	233 (7.9)	38 (8.5)	195 (7.8)	4931 (13.9)
20-24	808 (27.3)	136 (30.6)	672 (26.7)	10 253 (29.0)
25-29	884 (29.9)	117 (26.3)	767 (30.5)	9779 (27.6)
30-34	592 (20.0)	96 (21.6)	496 (19.7)	6712 (19.0)
≥35	443 (15.0)	58 (13.0)	385 (15.3)	3694 (10.4)
Missing data	1 (0.0)	—	1 (0.0)	1 (0.0)
Maternal race or ethnicity
White to non-Hispanic	1100 (37.1)	166 (37.3)	934 (37.1)	9943 (28.1)
Hispanic to any race	1424 (48.1)	205 (46.1)	1219 (48.4)	20 802 (58.8)
Black	149 (5.0)	33 (7.4)	116 (4.6)	1562 (4.4)
Asian/Pacific Islanders	214 (7.2)	35 (7.9)	179 (7.1)	2155 (6.1)
Others	74 (2.5)	6 (1.3)	68 (2.7)	908 (2.6)
US born
Yes	2133 (72.0)	314 (70.6)	1819 (72.3)	22 152 (62.6)
No	828 (28.0)	131 (29.4)	697 (27.7)	13 209 (37.3)
Missing data	—	—	—	9 (0.0)
Maternal education
Less than 8th grade	174 (5.9)	34 (7.6)	140 (5.6)	4518 (12.8)
9th to 12th grade	435 (14.7)	69 (15.5)	366 (14.5)	7583 (21.4)
High school graduate	937 (31.6)	152 (34.2)	785 (31.2)	10 909 (30.8)
Some degree less than college	923 (31.2)	131 (29.4)	792 (31.5)	7854 (22.2)
College or more	455 (15.4)	48 (10.8)	407 (16.2)	3925 (11.1)
Missing data	37 (1.2)	11 (2.5)	26 (1.0)	581 (1.6)

ASD=autism spectrum disorder; ID=intellectual disability. Data are number (%) or individuals.

^*Central Valley counties include San Joaquin, Stanislaus, Merced, Madera, Fresno, Kings, Tulare, and Kern.