Table 1.
Descriptive characteristics of mother-child dyads in pooled CANDLE and TIDES study population*
| Combined analytic population (N=1296) | By quartile of total OH-PAH** | ||||
|---|---|---|---|---|---|
| Quartile 1 (N=324) | Quartile 2 (N=324) | Quartile 3 (N=324) | Quartile 4 (N=324) | ||
| Maternal Variables | |||||
| Age, n (%) | |||||
| <20 years | 91 (7) | 6 (2) | 22 (7) | 31 (10) | 32 (10) |
| 20–<30 years | 588 (46) | 104 (33) | 152 (47) | 161 (50) | 171 (54) |
| 30–<40 years | 579 (45) | 197 (62) | 144 (45) | 124 (39) | 114 (36) |
| 40+ | 20 (2) | 10 (3) | 3 (1) | 5 (2) | 2 (1) |
| Missing | 18 | 7 | 3 | 3 | 5 |
| Education, n (%) | |||||
| Less than high school | 89 (7) | 11 (3) | 20 (6) | 17 (5) | 41 (13) |
| High school completion | 438 (34) | 41 (13) | 106 (33) | 146 (45) | 145 (45) |
| Graduated college or technical school | 425 (33) | 118 (37) | 114 (35) | 103 (32) | 90 (28) |
| Some graduate work or graduate/professional degree | 342 (26) | 153 (47) | 84 (26) | 58 (18) | 47 (15) |
| Missing | 2 | 1 | 0 | 0 | 1 |
| Race, n (%) | |||||
| White | 606 (47) | 230 (71) | 164 (51) | 132 (41) | 80 (25) |
| Black or African American | 566 (44) | 44 (14) | 128 (40) | 174 (54) | 220 (68) |
| Asian | 39 (3) | 19 (6) | 10 (3) | 4 (1) | 6 (2) |
| Native Hawaiian or other Pacific Islander | 2 (0) | 1 (0) | 0 (0) | 0 (0) | 1 (0) |
| American Indian or Alaska Native | 3 (0) | 0 (0) | 2 (1) | 1 (0) | 0 (0) |
| Other | 50 (4) | 17 (5) | 14 (4) | 7 (2) | 12 (4) |
| Multiple | 29 (2) | 13 (4) | 6 (2) | 6 (2) | 4 (1) |
| Missing | 1 | 0 | 0 | 0 | 1 |
| Ethnicity, n (%) | |||||
| Not Hispanic or Latino | 1237 (96) | 307 (95) | 310 (97) | 309 (96) | 311 (97) |
| Hispanic or Latino | 50 (4) | 16 (5) | 10 (3) | 13 (4) | 11 (3) |
| Missing | 9 | 0 | 4 | 2 | 2 |
| Prior live births, median (IQR) | 0.7 (1.13) | 0.28 (0.74) | 0.63 (0.93) | 0.87 (1.24) | 1 (1.37) |
| Missing | 0 | 0 | 0 | 0 | 0 |
| Maternal asthma, n (%) | |||||
| No | 1075 (84) | 266 (83) | 287 (89) | 263 (82) | 259 (81) |
| Yes | 207 (16) | 53 (17) | 35 (11) | 57 (18) | 62 (19) |
| Missing | 14 | 5 | 2 | 4 | 3 |
| Pre-pregnancy BMI, mean ± SD | 27.35 ± 7.37 | 25 ± 5.23 | 26.83 ± 7.33 | 28.37 ± 8.12 | 29.19 ± 7.79 |
| Missing | 0 | 0 | 0 | 0 | 0 |
| Child Variables | |||||
| Infant sex, (%) | |||||
| Male | 626 (48) | 149 (46) | 159 (49) | 147 (45) | 171 (53) |
| Female | 670 (52) | 175 (54) | 165 (51) | 177 (55) | 153 (47) |
| Missing | 0 | 0 | 0 | 0 | 0 |
| Preterm birth (< 37 weeks), n (%) | |||||
| No | 1179 (91) | 299 (92) | 293 (90) | 293 (90) | 294 (91) |
| Yes | 117 (9) | 25 (8) | 31 (10) | 31 (10) | 30 (9) |
| Missing | 0 | 0 | 0 | 0 | 0 |
| Birth weight (grams), mean ± SD | 3310 ± 522 | 3400 ± 505 | 3310 ± 542 | 3300 ± 505 | 3230 ± 526 |
| Missing | 0 | 0 | 0 | 0 | 0 |
| Child age (years) at outcome assessment | |||||
| Mean ± SD | 4.38 ± 0.38 | 4.43 ± 0.35 | 4.37 ± 0.38 | 4.35 ± 0.37 | 4.36 ± 0.41 |
| Missing | 0 | 0 | 0 | 0 | 0 |
| Postnatal secondhand smoke | |||||
| No | 1087 (84) | 307 (95) | 267 (83) | 269 (83) | 244 (76) |
| Yes | 206 (16) | 17 (5) | 56 (17) | 55 (17) | 78 (24) |
| Missing | 3 | 0 | 1 | 0 | 2 |
| Income at enrollment, n (%) | |||||
| <$15k | 236 (19) | 31 (10) | 50 (16) | 66 (21) | 89 (30) |
| $15k – $25k | 150 (12) | 16 (5) | 42 (13) | 42 (14) | 50 (17) |
| $25k – $45k | 191 (15) | 28 (9) | 55 (18) | 55 (18) | 53 (18) |
| $45k – $55k | 99 (8) | 23 (7) | 21 (7) | 23 (7) | 32 (11) |
| $55k – $65k | 71 (6) | 23 (7) | 14 (4) | 21 (7) | 13 (4) |
| $65k – $75k | 84 (7) | 28 (9) | 25 (8) | 18 (6) | 13 (4) |
| >=$75k | 410 (33) | 167 (53) | 107 (34) | 85 (27) | 51 (17) |
| Missing | 55 | 8 | 10 | 14 | 23 |
*
Characteristics are summarized for the entire analytic population, as well as by four quartiles of total PAH exposure, calculated as the sum of all SG-corrected concentrations of PAH metabolites. All characteristics were reported by mothers, except infant sex, birthweight, and preterm status, which were ascertained from birth medical records. Abbreviations: SD – standard deviation; BMI – body mass index; OH-PAH – mono-hydroxylated-polycyclic aromatic hydrocarbon.
**
Concentrations of total urinary OH-PAHs: quartile 1 (0–4.1), quartile 2 (4.2–7.0), quartile 3 (7.1–11.4) and quartile 4 (11.5–2433). All concentrations are in ng/mL.