Table 1.
Characteristics [n (%) or mean ± SD] of the Study to Explore Early Development population by outcome classification.
| Characteristic | ASD (n = 658) | DD (n = 771) | POP (n = 849) | ASD vs. POP p-Value |
DD vs. POP p-Value |
|---|---|---|---|---|---|
| Child sex | |||||
| Male | 537 (82) | 492 (64) | 449 (53) | ||
| Female | 121 (18) | 279 (36) | 400 (47) | <0.0001 | <0.0001 |
| Birth Year | |||||
| 2003–2004 | 267 (41) | 463 (60) | 458 (54) | ||
| 2005–2006 | 391 (59) | 308 (40) | 391 (46) | 0.02 | 0.01 |
| Maternal race/ethnicity | |||||
| Non-Hispanic White | 367 (56) | 478 (62) | 608 (72) | ||
| Other a | 291 (44) | 293 (38) | 241 (28) | <0.0001 | <0.0001 |
| Maternal education | |||||
| <Bachelor’s | 322 (49) | 335 (43) | 286 (34) | ||
| ≥Bachelor’s | 336 (51) | 436 (57) | 563 (66) | <0.0001 | 0.0002 |
| Maternal age at birth (years) | |||||
| <35 | 471 (72) | 538 (70) | 587 (69) | ||
| ≥35 | 187 (28) | 233 (30) | 262 (31) | 0.20 | 0.79 |
| Tobacco use during pregnancy | |||||
| Yes | 106 (16) | 106 (14) | 78 (9) | ||
| No | 552 (84) | 665 (86) | 771 (91) | <0.0001 | 0.004 |
| Preterm | |||||
| Yes | 109 (17) | 172 (22) | 80 (9) | ||
| No | 549 (83) | 599 (78) | 769 (91) | <0.0001 | <0.0001 |
| PM2.5 (µg/m3) (mean ± SD) | |||||
| Pregnancy | 12.8 ± 2.7 | 12.9 ± 2.6 | 12.7 ± 2.6 | 0.37 | 0.18 |
| First year of life | 12.7 ± 2.5 | 12.8 ± 2.5 | 12.5 ± 2.5 | 0.12 | 0.10 |
Numbers are N (%) or mean ± SD. ASD indicates autism spectrum disorder; DD, non-ASD developmental delays or disorders; PM2.5, particulate matter < 2.5 µm; POP, population-based control group; SD, standard deviation. a Includes African American, Asian, Hispanic, and all other.