Table 1.
Characteristics of eligible mothers and infants enrolled in the Healthy Start study, 2009–2014, and included in this analysis.
| Birthweight (N=1,125) | Adiposity at birth (n=951) | Adiposity at follow-up (n=574) | |
|---|---|---|---|
| Characteristic | Mean ± SD, Median (25th–75th percentile), or N (%) | ||
| Covariates | |||
| Maternal age (years) | 27.9 ± 6.2 | 27.9 ± 6.1 | 28.5 ± 6.1 |
| Pre-pregnancy body mass index (kg/m2) | 25.7 ± 6.2 | 25.7 ± 6.2 | 25.7 ± 6.3 |
| Normal weight/underweight (16.00–24.99) | 617 (55) | 520 (55) | 308 (54) |
| Overweight (25.00–29.99) | 282 (25) | 241 (25) | 155 (27) |
| Obese (30.00–65.41) | 226 (20) | 190 (20) | 111 (19) |
| Race/ethnicity | |||
| Non-Hispanic white | 604 (54) | 507 (53) | 318 (55) |
| Hispanic | 284 (25) | 239 (25) | 143 (25) |
| Non-Hispanic black | 170 (15) | 148 (16) | 80 (14) |
| All others | 67 (6) | 57 (6) | 33 (6) |
| Maternal education completed | |||
| Less than high school | 153 (14) | 128 (13) | 69 (12) |
| High school or equivalent | 204 (18) | 174 (18) | 84 (15) |
| Some college | 252 (22) | 215 (23) | 142 (25) |
| Four year college | 261 (23) | 220 (23) | 133 (23) |
| Graduate degree | 255 (23) | 214 (23) | 146 (25) |
| Year of birth | |||
| 2010 | 132 (12) | 123 (13) | 19 (3) |
| 2011 | 238 (21) | 205 (22) | 85 (15) |
| 2012 | 292 (26) | 243 (26) | 139 (24) |
| 2013 | 290 (26) | 241 (25) | 207 (36) |
| 2014 | 173 (15) | 139 (15) | 124 (22) |
| Season of birth | |||
| Winter | 249 (22) | 205 (22) | 138 (24) |
| Spring | 267 (24) | 231 (24) | 148 (26) |
| Summer | 338 (30) | 289 (30) | 147 (26) |
| Fall | 271 (24) | 226 (24) | 141 (25) |
| Maternal smoking during pregnancy (any) | 94 (8) | 80 (8) | 35 (6) |
| Previous pregnancies (any) | 737 (66) | 619 (65) | 374 (65) |
| Gestational weight gain (kg) | 13.9 ± 6.5 | 14.1 ± 6.4 | 13.7 ± 6.4 |
| Infant sex = male | 596 (53) | 492 (52) | 284 (49) |
| Gestational age at birth (days) | 277.1 ± 7.6 | 277.1 ± 7.6 | 277.3 ± 7.7 |
| Age at follow-up visit (days) | -- | -- | 155 ± 37 |
| Exclusively breastfed to follow-up visit | -- | -- | 218 (38) |
| Median income in Census tract (in $1000s) | 56.8 (44.8–83.6) | 56.7 (44.2–83.6) | 56.8 (44.1–84.1) |
| Persons below poverty level in Census tract (%) | 12.5 (6.8–23.1) | 12.8 (6.8–23.1) | 12.4 (6.6–22.5) |
| Outcomes | |||
| Birth weight (g) | 3286 ± 432 | 3290 ± 430 | 3280 ± 423 |
| Fat mass at birth (g) | -- | 293 ± 149 | 288 ± 140 |
| Fat free mass at birth (g) | -- | 2848 ± 330 | 2836 ± 324 |
| Adiposity at birth (%) | -- | 9.1 ± 3.9 | 9.0 ± 3.7 |
| Fat mass at follow-up visit (g) | -- | -- | 1677 ± 502 |
| Fat-free mass at follow-up visit (g) | -- | -- | 5146 ± 620 |
| Adiposity at follow-up visit (%) | -- | -- | 24.3 ± 5.4 |
| Rate of change in fat mass (g/day) | -- | -- | 9.3 ± 3.6 |
| Rate of change in fat-free mass (g/day) | -- | -- | 15.2 ± 3.1 |
| Rate of change in adiposity (%/100 days) | -- | -- | 10.4 ± 4.7 |
| Exposures | |||
| Trimester 1 average PM2.5 (μg/m3)a | 7.47 (6.80–8.13) | 7.48 (6.83–8.15) | 7.47 (6.81–8.09) |
| Trimester 2 average PM2.5 (μg/m3)b | 7.36 (6.76–8.06) | 7.36 (6.78–8.06) | 7.40 (6.78–8.04) |
| Trimester 3 average PM2.5 (μg/m3)c | 7.29 (6.74–8.06) | 7.29 (6.74–8.05) | 7.38 (6.75–8.21) |
| Full pregnancy average PM2.5 (μg/m3) | 7.45 (7.01–7.82) | 7.45 (7.02–7.83) | 7.46 (7.07–7.78) |
| Trimester 1 average 8-hr max O3 (ppb) | 41.9 (33.1–52.7) | 41.8 (32.9–52.6) | 44.1 (33.3–53.6) |
| Trimester 2 average 8-hr max O3 (ppb) | 43.6 (34.1–52.6) | 42.8 (33.9–52.3) | 43.4 (33.8–52.8) |
| Trimester 3 average 8-hr max O3 (ppb) | 46.3 (35.3–53.7) | 46.2 (35.5–53.7) | 44.7 (34.5–53.5) |
| Full pregnancy average 8-hr max O3 (ppb) | 44.0 (40.9–46.8) | 43.8 (40.8–46.8) | 44.0 (40.9–46.8) |
| Distance to highway (m) | 842 (396–1705) | 840 (396–1739) | 855 (410–1769) |
| Distance to non-highway major roadway (m) | 172 (72–321) | 171 (72–314) | 168 (70–312) |
| Traffic density <150m (vehicles*km/day) | 0 (0–2791) | 29 (0–2810) | 197 (0–2379) |
| Traffic density <250m (vehicles*km/day) | 3049 (0–9441) | 3276 (0–9494) | 3159 (0–9238) |
| Traffic density <500m (vehicles*km/day) | 23186 (9372–42615) | 23478 (8891–42485) | 22612 (8619–41102) |
| Traffic density <1000m (vehicles*km/day) | 111805 (63577–159922) | 112345 (64710–161232) | 111770 (62932–162629) |
Abbreviations: O3, ozone; PM2.5, particulate matter with diameter ≤ 2.5 micrometers.
a
Trimester 1 missing data due to >25% missing monitor values: 73 for birthweight, 61 for adiposity at birth, 40 for adiposity at follow-up.
b
Trimester 2 missing data due to >25% missing monitor values: 76 for birthweight, 64 for adiposity at birth, 33 for adiposity at follow-up.
c
Trimester 3 missing data due to >25% missing monitor values: 20 for birthweight, 17 for adiposity at birth, 10 for adiposity at follow-up.