Table 2.
Characteristics of Children With Autism Spectrum Disorder, Typical Development, and Developmental Delaya
| Characteristic | Typical Development (n = 40 295) |
Autism Spectrum Disorder (n = 195) |
Developmental Delay (n = 4636) |
P Value | |
|---|---|---|---|---|---|
| Autism Spectrum Disorder vs Typical Development | Autism Spectrum Disorder vs Developmental Delay | ||||
| Sex | |||||
| Male | 19 201 (47.7) | 158 (81.0) | 3490 (75.3) | <.001 | .07 |
| Female | 21 094 (52.3) | 37 (19.0) | 1146 (24.7) | ||
| Birth year | |||||
| 2002 | 3947 (9.8) | 34 (17.4) | 458 (9.9) | <.001 | <.001 |
| 2003 | 5806 (14.4) | 53 (27.2) | 673 (14.5) | ||
| 2004 | 6041 (15.0) | 28 (14.4) | 704 (15.2) | ||
| 2005 | 6736 (16.7) | 21 (10.8) | 762 (16.4) | ||
| 2006 | 7314 (18.2) | 28 (14.4) | 835 (18.0) | ||
| 2007 | 5962 (14.8) | 16 (8.2) | 668 (14.4) | ||
| 2008 | 4489 (11.1) | 15 (7.7) | 536 (11.6) | ||
| Maternal educational level, y | |||||
| <12 | 6385 (15.8) | 42 (21.5) | 878 (18.9) | .02 | .07 |
| 12 | 4540 (11.3) | 30 (15.4) | 497 (10.7) | ||
| 13–16 | 18 794 (46.6) | 81 (41.5) | 1980 (42.7) | ||
| ≥17 | 10 576 (26.2) | 42 (21.5) | 1281 (27.6) | ||
| Maternal age, y | |||||
| <25 | 3561 (8.8) | 23 (11.8) | 416 (9.0) | .37 | .28 |
| 25–29 | 13 491 (33.5) | 66 (33.8) | 1402 (30.2) | ||
| 30–34 | 16 108 (40.0) | 69 (35.4) | 1890 (40.8) | ||
| ≥35 | 7135 (17.7) | 37 (19.0) | 928 (20.0) | ||
| Maternal smoking | |||||
| Yes | 3010 (7.5) | 23 (11.8) | 363 (7.8) | .02 | <.05 |
| No | 37 285 (92.5) | 172 (88.2) | 4273 (92.2) | ||
| Mode of delivery | |||||
| Spontaneous | 32 064 (79.6) | 152 (77.9) | 3540 (76.4) | .56 | .29 |
| Induced | 5410 (13.4) | 31 (15.9) | 663 (14.3) | ||
| Cesarean section | 2821 (7.0) | 12 (6.2) | 433 (9.3) | ||
| Gestational age, wk | |||||
| <37 | 2247 (5.6) | 14 (7.2) | 410 (8.8) | .33 | .42 |
| ≥37 | 38 048 (94.4) | 181 (92.8) | 4226 (91.2) | ||
| Breastfeeding | |||||
| Yes | 39 771 (98.7) | 189 (96.9) | 4546 (98.1) | .03 | .27 |
| No | 524 (1.3) | 6 (3.1) | 90 (1.9) | ||
| Parity | |||||
| 0 | 19 303 (47.9) | 103 (52.8) | 2252 (48.6) | .17 | .25 |
| ≥1 | 20 992 (52.1) | 92 (47.2) | 2384 (51.4) | ||
| Birth weight, mean (SD), g | 3578 (566) | 3544 (606) | 3508 (658) | .51 | .65 |
| Child BMI at 36 mo, mean (SD) | 16.1 (1.4) | 16.3 (1.6) | 16.2 (1.4) | .59 | .85 |
| GI symptoms at 6–18 mo | |||||
| Diarrhea | 18 562 (46.1) | 96 (49.2) | 2169 (46.8) | .38 | .50 |
| Constipation | 3992 (9.9) | 39 (20.0) | 552 (11.9) | <.001 | <.01 |
| Food allergy/intolerance | 2789 (6.9) | 24 (12.3) | 382 (8.2) | <.01 | .04 |
| Any GI symptomb | 21 098 (52.4) | 118 (60.5) | 2521 (54.4) | .02 | .09 |
| GI symptoms at 18–36 mo | |||||
| Diarrhea | 1808 (4.5) | 22 (11.3) | 253 (5.5) | <.001 | <.01 |
| Constipation | 6202 (15.4) | 40 (20.5) | 793 (17.1) | <.05 | .22 |
| Food allergy/intolerance | 2548 (6.3) | 25 (12.8) | 365 (7.9) | <.001 | .01 |
| Any GI symptomb | 9359 (23.2) | 74 (37.9) | 1230 (26.5) | <.001 | <.001 |
| Language delay at 36 mo | 0 | 104 (53.3) | 1818 (39.2) | – | <.001 |
| Motor delay at 36 mo | 0 | 76 (39.0) | 3196 (68.9) | – | <.001 |
Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); GI, gastrointestinal.
a
Data are presented as number (percentage) of participants unless otherwise indicated.
b
Any GI symptom includes diarrhea, constipation, and food allergy/intolerance.