Table 2.
Characteristics of eligible cases and matched controls. Data come from (a) birth certificates, (b) American Community Survey, or (c) the parent interview/medical provider follow-up.
| 2 (a) Birth certificate | Enrolled cases (n=661) | Eligible controls (n=12,050) | Enrolled controls (n=2774) | |
|---|---|---|---|---|
| Characteristic | ||||
| Maternal race/ethnicity, n (%) | ||||
| White, non-Hispanic | 268 (46.7) | 5055 (43.2) | 1488 (54.7) | |
| Black, non-Hispanic | 127 (22.1) | 2257 (19.3) | 420 (15.4) | |
| Hispanic | 52 (9.1) | 1072 (9.2) | 186 (6.8) | |
| Other, non-Hispanic | 127 (22.1) | 3312 (28.3) | 628 (23.1) | |
| Unknown | 87 | 354 | 52 | |
| Maternal education level, n (%) | ||||
| Less than high school | 110 (20.2) | 2516 (22.9) | 420 (16.8) | |
| High school equivalent | 130 (23.9) | 2905 (26.4) | 529 (21.2) | |
| Some college | 146 (26.8) | 2851 (26.0) | 690 (27.6) | |
| College degree or more | 158 (29.0) | 2714 (24.7) | 857 (34.3) | |
| Unknown | 117 | 1064 | 278 | |
| Source of payment for birth, n (%) | ||||
| Private | 228 (48.2) | 4238 (44.9) | 1120 (52.9) | |
| Public/state | 223 (47.1) | 4707 (49.9) | 893 (42.1) | |
| Uninsured | 8 (1.7) | 232 (2.5) | 41 (1.9) | |
| Other | 14 (3.0) | 264 (2.8) | 65 (3.1) | |
| Unknown | 188 | 2609 | 655 | |
| Adequacy of Prenatal Care Utilization Index, n (%) | ||||
| Adequate Plus | 183 (34.9) | 3377 (31.4) | 814 (33.0) | |
| Adequate | 186 (35.5) | 4130 (38.4) | 972 (39.5) | |
| Intermediate | 67 (12.8) | 1360 (12.6) | 272 (11.0) | |
| Inadequate | 88 (16.8) | 1888 (17.6) | 405 (16.4) | |
| Unknown | 137 | 1295 | 311 | |
| 2 (b) American Community Survey | ||||
| Not successfully geocoded, n (%) | 9 (1.4) | 179 (1.5) | 20 (0.7) | |
| Median income, n (%) | ||||
| ≤$15,000 | 37 (5.7) | 796 (6.7) | 150 (5.4) | |
| >$15,000 to ≤$30,000 | 374 (57.4) | 6802 (57.4) | 1485 (53.9) | |
| >$30,000 to ≤$45,000 | 191 (29.3) | 3315 (28) | 849 (30.8) | |
| >$45,000 to ≤$60,000 | 37 (5.7) | 711 (6.0) | 204 (7.4) | |
| >$60,000 | 13 (2.0) | 232 (2.0) | 66 (2.4) | |
| Crowding, median % (IQR) | ||||
| 0.50 or less occupants per room | 68.2 (52.8,77) | 67.1 (50.6,77) | 69.3 (55,78.1) | |
| 0.51 to 1.00 occupants per room | 28.6 (20.9,38.5) | 29.7 (22,38.5) | 27.5 (19.8,37.4) | |
| 1.01 to 1.50 occupants per room | 2.2 (1.1,5.5) | 2.2 (1.1,6.6) | 2.2 (0,5.5) | |
| 1.51 to 2.00 occupants per room | 0 (0,2.2) | 0 (0,2.2) | 0 (0,2.2) | |
| 2.01 or more occupants per room | 0 (0,0) | 0 (0,1.1) | 0 (0,0) | |
| Poverty, median % (IQR) | ||||
| <100% of poverty level | 15.4 (7.7,25.3) | 16.5 (8.8,26.4) | 13.2 (7.7,24.2) | |
| 100–149% of poverty level | 9.9 (5.5,14.3) | 9.9 (5.5,15.4) | 9.9 (5.5,14.3) | |
| ≥150% of poverty level | 73.7 (59.4,85.8) | 72.6 (58.3,84.7) | 75.9 (61.6,86.9) | |
| Gini Index, n (%)a | ||||
| 0.2 to <0.3 | 17 (2.6) | 148 (1.2) | 56 (2.0) | |
| 0.3 to <0.4 | 255 (39.1) | 4537 (38.3) | 1146 (41.6) | |
| 0.4 to <0.5 | 325 (49.8) | 6092 (51.4) | 1324 (48.1) | |
| 0.5 to <0.6 | 52 (8.0) | 1030 (8.7) | 219 (8.0) | |
| 0.6 to <0.7 | 3 (0.5) | 48 (0.4) | 9 (0.3) | |
| 0.7 to <0.8 | 0 | 0 | 0 | |
| Census tract is >25% foreign born, n (%) | 204 (31.3) | 4120 (34.8) | 804 (29.2) | |
| 2(c) Parent interview/medical provider follow-up | ||||
| Median age, months (range) | 21 (2-59) | 21 (2-60) | ||
| Asthma, n (%) | 128 (19.4) | 321 (11.6) | ||
| Chronic condition, n (%) | 51 (7.7) | 32 (1.2) | ||
| Immunocompromising condition, n (%) | 111 (16.8) | 82 (3.0) | ||
| Breastfeeding, n (%) | ||||
| Ever breastfed | 480 (73.2) | 2224 (80.4) | ||
| Currently breastfed | 52 (7.9) | 303 (11.0) | ||
| Crowding (>2 people per bedroom) | 111 (16.8) | 414 (15) | ||
| Day care attendance, n (%) | 313 (47.5) | 957 (34.6) | ||
| Smoking exposure, n (%) | 134 (20.5) | 443 (16.1) | ||
| Recent influenza infection, n (%) | 20 (3.2) | 25 (1) | ||
| Influenza vaccination in last 6 months, n (%) | 184 (27.8) | 830 (30) | ||
| Household income, n (%) | ||||
| ≤$15,000 | 166 (27.9) | 474 (18.5) | ||
| >$15,000 to ≤$30,000 | 100 (16.8) | 455 (17.7) | ||
| >$30,000 to ≤$45,000 | 53 (8.9) | 259 (10.1) | ||
| >$45,000 to ≤$60,000 | 65 (10.9) | 286 (11.1) | ||
| >$60,000 | 192 (32.3) | 975 (38) | ||
| Refused | 19 (3.2) | 119 (4.6) | ||
| Unknown | 66 | 206 | ||
| Insurance type at IPD, n (%) | ||||
| Private | 288 (44.4) | 1449 (52.7) | ||
| Public | 344 (53.1) | 1227 (44.7) | ||
| Uninsured | 15 (2.3) | 54 (2.0) | ||
| Other | 0 | 4 (0.1) | ||
| Refused | 1 (0.2) | 13 (0.5) | ||
| Unknown | 13 | 27 | ||
| Race/ethnicity, n (%) | ||||
| White, non-Hispanic | 259 (39.4) | 1368 (49.4) | ||
| Black, non-Hispanic | 165 (25.1) | 469 (16.9) | ||
| Hispanic | 64 (9.7) | 191 (6.9) | ||
| Other, non-Hispanic | 169 (25.7) | 739 (26.7) | ||
| Unknown | 4 | 7 | ||
| Primary caregiver education level, n (%) | ||||
| Less than high school | 78 (12.0) | 289 (10.6) | ||
| High school equivalent | 134 (20.7) | 515 (18.8) | ||
| Some college | 193 (29.8) | 661 (24.2) | ||
| College degree or more | 243 (37.5) | 1272 (46.5) | ||
| Unknown | 13 | 37 | ||
a
Measure of income inequality for a geographic area where zero indicates absolute equality and one indicates total inequality.