Table 1.
Frequency distribution of birth and demographic characteristics across cases and controls
| Residing within 15 miles of an air monitor | ||
|---|---|---|
| Variable name | Cases (n=337) Frequency (%) | Controls (n=96,514) Frequency (%) |
| Child's gender | ||
| Male | 154 (45.7) | 49165 (50.9) |
| Female | 183 (54.3) | 47349 (49.1) |
| Birth type | ||
| Singleton | 328 (97.3) | 94014 (97.4) |
| Multiple birth | 9 (2.7) | 2500 (2.6) |
| Maternal age at child birth | ||
| <20 | 39 (11.6) | 10133 (10.5) |
| 20-29 | 150 (44.5) | 48628 (50.4) |
| 30-34 | 101 (30.0) | 23218 (24.1) |
| ≥35 | 47 (14.0) | 14524 (15.0) |
| Missing | 0 (0.0) | 11 (0.0) |
| Maternal race/ethnicity | ||
| Non-Hispanic white | 107 (31.8) | 27079 (28.1) |
| Hispanic of any race | 161 (47.8) | 47693 (49.4) |
| Other (black, Asian/Pacific Islander, other) | 68 (20.2) | 21284 (22.0) |
| Missing | 1 (0.3) | 458 (0.5) |
| Parity | ||
| Nulliparous | 138 (41.0) | 38540 (39.8) |
| One child | 100 (29.7) | 30119 (31.2) |
| Two or more children | 99 (29.4) | 27945 (29.0) |
| Census-based SES* | ||
| 1 (Lowest) | 77 (22.9) | 27212 (28.2) |
| 2 | 78 (23.2) | 22230 (23.0) |
| 3 | 68 (20.2) | 18235 (18.9) |
| 4 | 64 (19.0) | 15359 (15.9) |
| 5 (Highest) | 50 (14.8) | 13445 (13.9) |
| Missing | 0 (0.0) | 33 (0.0) |
*
Index created by combining 7 census block group indicators: education, median household income, percent living <200% poverty level, percent blue-collar workers, percent > 16 years in workforce without job, median rent, and median housing value.
PI, Pacific Islander; SES, socioeconomic status.