Table 1:
Characteristics of 515 eligible mother-infant pairs in the Healthy Start Study.
| Characteristic | Mean ± SD, Median (IQR), or N (%) |
|---|---|
| Covariates | |
| Maternal age at delivery (years) | 27.6 ± 6.2 |
| Pre-pregnancy body mass index (kg/m2) | 25.9 ± 6.5 |
| Race/ethnicity | |
| Hispanic | 128 (25) |
| Non-Hispanic white | 273 (53) |
| Non-Hispanic black | 79 (15) |
| All others | 35 (7) |
| Maternal smoking during pregnancy (any) | 49 (10) |
| Median annual income in the Census tract (per $1,000) | 64.1 ± 26.7 |
| Maternal education completed | |
| Less than 12th grade | 79 (15) |
| High school degree or GED | 95 (18) |
| Some college or Associate’s degree | 106 (21) |
| Four years of college (BA, BS) | 115 (22) |
| Graduate degree (Master’s, Ph.D.) | 120 (23) |
| Season of conception | |
| Winter | 163 (32) |
| Spring | 97 (19) |
| Summer | 90 (18) |
| Fall | 165 (32) |
| Mode of delivery= Caesarean | 110 (21) |
| Previous pregnancy | 323 (63) |
| Season of birth | |
| Winter | 109 (21) |
| Spring | 136 (26) |
| Summer | 148 (29) |
| Fall | 122 (24) |
| Infant sex = male | 276 (54) |
| Gestational age at sample collection (days) | 191 ± 17 |
| Gestational age at birth (days) | 276 ± 9 |
| Age at follow-up visit (months) a | 5.1 ± 1.2 |
| Exposures | |
| Average PM2.5 (μg/m3) a | |
| Prior 30 days from sample collection | 7.13 (6.08-8.26) |
| Prior 7 days from sample collection | 6.92 (5.53-8.61) |
| Trimester 1 | 7.52 (6.89-8.14) |
| Trimester 2 | 7.39 (6.78-8.09) |
| Trimester 3 | 7.48 (6.84-8.29) |
| Full Pregnancy | 7.51 (7.13-7.86) |
| Prior 30 days to delivery | 7.24 (6.33-8.42) |
| Prior 7 days to delivery | 6.73 (5.58-8.20) |
| Average 8-hr max O3 (ppb) | |
| Prior 30 days to sample collection | 45.1 (32.7-54.2) |
| Prior 7 days to sample collection | 44.1 (33.4-54.6) |
| Trimester 1 | 42.1 (33.8-53.7) |
| Trimester 2 | 42.6 (33.9-52.3) |
| Trimester 3 | 46.1 (35.0-54.6) |
| Full Pregnancy | 44.0 (40.9-47.1) |
| Prior 30 days to delivery | 48.0 (34.1-55.9) |
| Prior 7 days to delivery | 47.0 (35.4-55.3) |
| Outcomes | |
| Birth weight (g) | 3275 ± 427 |
| Fat mass at birth (g) a | 285.3 ± 143.1 |
| Fat free mass at birth (g) a | 2843.4 ± 333.9 |
| Adiposity at birth (%) a | 8.9 ± 3.8 |
| Fat mass at postnatal follow-up visit (g) a | 1708.6 ± 526.8 |
| Fat free mass at postnatal follow-up visit (g) a | 5167 ± 643.4 |
| Adiposity at postnatal follow-up visit (%) a | 24.5 ± 5.6 |
Abbreviations: SD, standard deviation; IQR, interquartile range; PM2.5, particulate matter with diameter ≤ 2.5 micrometers; O3, average 8-hour maximum ozone concentration in parts per billion.
Missing data for the following variables (n=number missing): age at postnatal follow-up, n=181; average PM2.5 Prior 30 days to sample collection, n=31; average PM2.5 Prior 7 days to sample collection, n=30; average PM2.5 Trimester 1, n=46; average PM2.5 Trimester 2, n=44; average PM2.5 Trimester 3, n=17; average PM2.5 Prior 30 days to delivery, n=31; average PM2.5 Prior 7 days to delivery, n=32; average PM2.5 Full pregnancy, n=4; fat mass at birth, n=18; fat free mass at birth, n=18; adiposity at birth, n=18; fat mass at poshiatal follow-up, n=181; fat free mass at postnatal follow-up, n=181; adiposity at postnatal follow-up, n=181.