TABLE 2.

Characteristics of ASD (n = 976) and Non-ASD (n = 96 736) Children Included in the DNBC and Characteristics of the Background Population (N = 529 465)

Characteristic	DNBC, ASD, n (%)	DNBC, Non-ASD, n (%)	All Children Born in Denmark, 1996–2003, n (%)
Offspring characteristics
Gender
Male	792 (81.1)	48 808 (51.0)	271 898 (51.3)
Female	184 (18.9)	46 952 (49.0)	257 567 (48.7)
Gestational age, wk
<37	56 (5.7)	5971 (6.2)	33 960 (6.4)
≥37	916 (93.9)	89 497 (93.5)	492 062 (92.9)
Missing	4 (0.4)	292 (0.3)	3443 (0.7)
Year of birth
1996–1998	364 (37.3)	32 643 (34.1)	201 654 (38.1)
1999–2000	432 (44.3)	41 192 (43.0)	133 490 (25.2)
2001–2003	180 (18.4)	21 925 (22.9)	194 321 (36.7)
Parental characteristics
Mother’s age, y
<21	13 (1.3)	553 (0.6)	8671 (1.6)
21–25	120 (12.3)	8480 (8.9)	70 823 (13.4)
26–30	344 (35.3)	36 444 (38.1)	191 579 (36.2)
31–34	344 (35.3)	35 765 (37.4)	180 062 (34.0)
≥35	155 (15.9)	14 518 (15.2)	78 330 (14.8)
Father’s age, y
<26	58 (5.9)	4126 (4.3)	36 078 (6.8)
26–30	258 (26.4)	25 327 (26.5)	139 493 (26.4)
31–35	360 (36.9)	37 622 (39.3)	192 215 (36.3)
≥35	291 (29.8)	28 264 (29.5)	156 804 (29.6)
Missing	9 (0.9)	421 (0.4)	4875 (0.9)
Parity
1	499 (51.1)	43 497 (45.4)	222 357 (42.0)
2+	447 (45.8)	49 739 (51.9)	291 892 (55.1)
Missing	30 (3.1)	2524 (2.6)	15 216 (2.9)
Parental psychiatric disorder
Yes	77 (7.9)	3688 (3.9)	22 089 (4.2)
No	899 (92.1)	92 072 (96.2)	507 376 (95.8)
Maternal smoking during pregnancy
Yes	205 (21.0)	16 258 (17.0)	114 465 (21.6)
No	734 (75.2)	76 155 (79.5)	390 805 (73.8)
Missing	37 (3.8)	3347 (3.5)	24 195 (4.6)
Parental educational status
Academic level	548 (56.2)	57 126 (59.7)	—
Beyond compulsory school	284 (29.1)	24 939 (26.0)	—
Compulsory school	45 (4.6)	3430 (3.6)	—
Missing	99 (10.1)	10 265 (10.7)	—

—, data not available.