Table 1.
Characteristics of the study sample grouped by the level of the cord blood PAH-DNA adducts (N = 339)
| Total N=339 |
Low prenatal PAH exposure (PAH adducts ≤ 0.250 per 108 nucleotides) N=119 |
High prenatal PAH exposure (PAH adducts > 0.250 per 108 nucleotides) N=220 |
P-level for difference |
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|---|---|---|---|---|---|
|
| |||||
| Maternal age: ≤ 25years | n (%) | 78 (23.0) | 25 (21.0) | 53 (24.1) | 0.380 |
| 26–30 years | n (%) | 191 (56.3) | 73 (61.3) | 118 (53.6) | |
| > 30 years | n (%) | 70 (20.6) | 21 (17.6) | 49 (22.3) | |
|
| |||||
| Maternal education: | |||||
| Elementary | n (%) | 32 (9.4) | 8 (6.7) | 24 (10.9) | 0.163 |
| Secondary | n (%) | 78 (23.0) | 23 (19.3) | 55 (25.0) | |
| Higher | n (%) | 229 (67.6) | 88 (73.9) | 141 (64.1) | |
|
| |||||
| Gender: Boys | n (%) | 170 (50.1) | 64 (53.8) | 106 (48.2) | 0.384 |
| Girls | n (%) | 169 (49.9) | 55 (46.2) | 114 (51.8) | |
|
| |||||
| Parity: 1 | n (%) | 217 (64.0) | 79 (66.4) | 138 (62.7) | 0.581 |
| ≥ 2 | n (%) | 122 (36.0) | 40 (33.6) | 82 (37.3) | |
|
| |||||
| Breastfeeding: ≤ 6 months | n (%) | 105 (31.0) | 33 (27.7) | 72 (32.7) | 0.4085 |
| > 6 months | n (%) | 234 (69.0) | 86 (72.3) | 148 (67.3) | |
|
| |||||
| Maternal atopy (+): | n (%) | 85 (25.1) | 32 (26.9) | 53 (24.1) | 0.663 |
|
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| Prenatal ETS (+): | n (%) | 81 (23.9) | 29 (24.4) | 52 (23.6) | 0.986 |
|
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| Postnatal ETS (+): | n (%) | 63 (18.6) | 25 (21.0) | 38 (17.3) | 0.485 |
|
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| Mould (+) or dampness: | n (%) | 104 (30.7) | 32 (26.9) | 72 (32.7) | 0.3227 |
|
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| Prenatal exposure to fine particulate matter (PM2.5 μg/m3): Median |
33.4 | 31.8 | 35.1 | 0.087 | |
| IQ range | 22.3–50.7 | 22.3–44.8 | 22.2–53.8 | ||
| Missing data | 3 | 1 | 2 | ||
|
| |||||
| Cord blood cotinine (ng/mL): Median | 0.08 | 0.08 | 0.08 | 0.201 | |
| IQ range | 0.05–0.15 | 0.05–0.16 | 0.05–0.14 | ||
| Missing data | 15 | 4 | 11 | ||