Table 2. Subjects [no. (%)] and univariate ORs according to socioeconomic, demographic, maternal and fetal characteristics, and the exposure to the three indicators of air pollution between cases of LBW and controls.
| Antenatal care** | Cases (%) | Controls (%) | OR (95%CI) | ||
| No visits | 111 (1.9%) | 53 (0.9%) | 2.35 (1.69; 3.27) | ||
| 1 to 3 | 359 (6.4%) | 226 (3.9%) | 1.78 (1.50; 2.12) | ||
| 4 to 6 | 1398 (24.7%) | 1207 (21.0%) | 1.30 (1.19; 1.42) | ||
| ≥7 | 3795 (67.0%) | 4263 (74.2%) | 1.0 | ||
| Maternal education** | |||||
| ≤3 years | 271 (4.8%) | 240 (4.2%) | 1.39(1.14; 1.68) | ||
| 4 to7 years | 1375 (24.1%) | 1142 (19.8%) | 1.48 (1.31; 1.66) | ||
| 8 to 12 years | 3075 (54.0%) | 3180 (55.3%) | 1.18 (1.07; 1.31) | ||
| >12 years | 974 (17.1%) | 1194 (20.7%) | 1.0 | ||
| Number of previous births** | |||||
| No child | 3151 (54.6%) | 2767 (47.6%) | 1.36 (1.26; 1.47) | ||
| 1 to 3 | 2331 (40.3%) | 2792 (47.9%) | 1.0 | ||
| ≥4 | 290 (5.0%) | 255 (4.4%) | 1.36 (1.14; 1.63) | ||
| Marital status** | |||||
| Single | 3644 (63.7%) | 3412 (59.0%) | 1.26 (1.16; 1.36) | ||
| Married | 1913 (33.4%) | 2267 (38.9%) | 1.0 | ||
| Widow | 13 (0.2%) | 11 (0.2%) | 1.39 (0.62; 3.11) | ||
| Separed/divorced | 66 (1.2%) | 65 (1.1%) | 1.19 (0.84; 1.69) | ||
| Consensual union | 87 (1.5%) | 41 (0.7%) | 2.47 (1.69;3.60) | ||
| Maternal age** | |||||
| <20 | 1009 (17.5%) | 812 (14.0%) | 1.32 (1.19; 1.47) | ||
| 20 to 29 | 2831 (49.0%) | 3004 (51.7%) | 1.0 | ||
| 30 to 39 | 1736 (30.1%) | 1822 (31.3%) | 1.01 (0.93; 1.10) | ||
| ≥40 | 196 (3.4%) | 176 (3.0%) | 1.18 (0.96; 1.46) | ||
| Number of previous stillbirths** | |||||
| No child | 5283 (91.5%) | 5433 (93.4%) | 1.0 | ||
| ≥1 | 489 (8.5%) | 381 (6.6%) | 1.32 (1.15; 1.51) | ||
| Delivery | |||||
| Vaginal | 2814 (48.8%) | 2746 (47.3%) | 1.0 | ||
| Cesarean | 2951 (51.2%) | 3065 (52.7%) | 0.94 (0.88; 1.01) | ||
| Neighborhood-level income † ** | |||||
| <3.35 | 1495 (25.9%) | 1393 (23.7%) | 1.25 (1.13; 1.39) | ||
| 3.35 to <4.62 | 1500 (26.0%) | 1412 (24.3%) | 1.22 (1.10; 1.35) | ||
| 4.62 to 7.16 | 1423 (24.7%) | 1472 (25.3%) | 0.98 (0.98; 1.23) | ||
| ≥7.16 | 1350 (23.4%) | 1553 (26.7%) | 1.0 | ||
| Race/ethnicity** | |||||
| White | 3217 (66.4%) | 3397 (70.2%) | 1.0 | ||
| Black | 110 (2.3%) | 73 (1.5%) | 1.59 (1.18; 2.15) | ||
| Asian | 19(0.4%) | 29 (0.6%) | 0.7 (0.4; 1.24) | ||
| Mixed races | 1501 (30.9%) | 1343 (27.7%) | 1.18 (1.08; 1.29) | ||
| Gender | |||||
| Male | 2444 (42.0%) | 2425 (42.0%) | 1.0 | ||
| Female | 3347 (58.0%) | 3370 (58.0%) | 1.00 (0.93; 1.08) | ||
| LUR-PM10 (µg/m3)** | |||||
| <35.3 | 1580 (27.4%) | 1372 (23.9%) | 1.0 | ||
| 35.3 to <37.0 | 1441 (24.5%) | 1379 (23.7%) | 0.92 (0.83; 1.02) | ||
| 37.0 to <40.4 | 1404 (24.3%) | 1493 (25.7%) | 0.85 (0.76; 0.94) | ||
| 40.4 to ≤108.2 | 1375 (23.8%) | 1521 (26.2%) | 0.81 (0.73; 0.90) | ||
| DWTD (vehicles/hour)* | |||||
| <22.5 | 1484 (26.1%) | 1372 (23.9%) | 1.0 | ||
| 22.5 to <188.7 | 1441 (25.4%) | 1415 (24.7%) | 0.94 (0.85; 1.04) | ||
| 188.7 to <763.6 | 1392 (24.5%) | 1464 (25.5%) | 0.88 (0.79; 0.97) | ||
| 763.6 to ≤10,331.1 | 1367 (24.0%) | 1489 (25.9%) | 0.85 (0.76; 0.94) | ||
| Distance (meters) § | |||||
| <150 | 844 (15.2%) | 881 (14.6%) | 0.96 (0.87; 1.06) | ||
| ≥150 | 4928 (84.8%) | 4933 (85.4%) | 1.0 | ||
| Distance (meters) § * | |||||
| <249.4 | 1394 (24.2%) | 1501 (25.8%) | 0.87 (0.78; 0.96) | ||
| 249.4 to <547.0 | 1397 (24.2%) | 1501 (25.8%) | 0.87 (0.78;0.96) | ||
| 547.0 to <1,126.4 | 1484 (25.7%) | 1413 (24.3%) | 0.98 (0.88; 1.01) | ||
| 1,126.4 to ≤22,263.7 | 1497 (25.9%) | 1399 (24.1%) | 1.0 | ||
χ2 test **p≤0.001, *p≤0.01.
†
quartiles of minimum wages.
§
Shortest distance to roads ≥95th percentile of traffic.