Table 1.
Participant characteristics by categories of pooled proximity to major roads before age 3 years.
| Characteristics | Total (n = 920), n (%) |
Pooled Proximity to Major Road before Age 3 Years, Meters | ||||
|---|---|---|---|---|---|---|
| <100 (n = 58), n (%) | 100–200 (n = 82), n (%) | 201–300 (n = 101), n (%) | >300 (n = 679), n (%) | p-Value * | ||
| Age at enrollment, months | 0.19 | |||||
| <2 | 271 (29) | 19 (33) | 16 (20) | 33 (33) | 203 (30) | |
| ≥2 | 649 (71) | 39 (67) | 66 (80) | 68 (67) | 476 (70) | |
| Sex | 0.18 | |||||
| Male | 552 (60) | 29 (50) | 44 (54) | 65 (64) | 414 (61) | |
| Female | 368 (40) | 29 (50) | 38 (46) | 36 (36) | 265 (39) | |
| Race/ethnicity | <0.001 | |||||
| Non-Hispanic white | 400 (43) | 19 (33) | 30 (37) | 48 (47) | 303 (45) | |
| Non-Hispanic black | 210 (23) | 20 (34) | 33 (40) | 26 (26) | 131 (19) | |
| Hispanic | 275 (30) | 15 (26) | 17 (21) | 27 (27) | 216 (32) | |
| Other | 35 (4) | 4 (7) | 2 (2) | 0 (0) | 29 (4) | |
| Health insurance | 0.46 | |||||
| Non-private (e.g., public or none) | 547 (60) | 40 (69) | 46 (58) | 62 (61) | 399 (59) | |
| Private | 371 (40) | 18 (31) | 34 (42) | 39 (39) | 280 (41) | |
| Median household income estimated by ZIP code at enrollment | 0.93 | |||||
| <$50,000 | 481 (52) | 32 (55) | 41 (50) | 54 (53) | 354 (52) | |
| ≥$50,000 | 439 (48) | 26 (45) | 41 (50) | 47 (47) | 325 (48) | |
| Mother’s age at enrollment, years | 0.51 | |||||
| <25 | 289 (31) | 23 (40) | 28 (34) | 29 (29) | 209 (31) | |
| 25–29 | 263 (29) | 12 (20) | 24 (30) | 34 (34) | 193 (29) | |
| 30–34 | 218 (24) | 11 (19) | 15 (18) | 20 (20) | 172 (25) | |
| ≥35 | 148 (16) | 12 (21) | 15 (18) | 17 (17) | 104 (15) | |
| Mode of delivery | 0.59 | |||||
| Vaginal delivery | 596 (66) | 41 (73) | 56 (68) | 64 (65) | 435 (65) | |
| Cesarean section | 312 (34) | 15 (27) | 26 (32) | 34 (35) | 237 (35) | |
| Premature birth (gestational age ≤37 weeks) | 170 (18) | 13 (22) | 13 (16) | 21 (21) | 123 (18) | 0.71 |
| Infant tobacco exposure at enrollment | 138 (15) | 3 (5) | 13 (16) | 19 (19) | 103 (15) | 0.13 |
| Parental history of asthma | 305 (33) | 19 (33) | 29 (35) | 32 (32) | 225 (33) | 0.91 |
| Parental history of eczema | 175 (19) | 18 (31) | 15 (18) | 21 (21) | 121 (18) | 0.09 |
* All of the p-values obtained by excluding participants with any missing data.