Table 3.
Interquartile increase in ambient air pollution and risk of fetal growth restriction and small-for-gestational age birtha by window of exposureb
| Whole pregnancy |
3 months preconception |
Trimester 1 |
Trimester 2 |
Trimester 3 |
|
|---|---|---|---|---|---|
| RR (95% CI) | RR (95% CI) | RR (95% CI) | RR (95% CI) | RR (95% CI) | |
| Fetal growth restriction | |||||
| Sulfur dioxide | 1.16 (1.08, 1.25) | 1.15 (1.09, 1.23) | 1.11 (1.04, 1.18) | 1.13 (1.06, 1.20) | 1.16 (1.09, 1.24) |
| Ozone | 0.87 (0.81, 0.94) | 0.88 (0.83, 0.94) | 0.92 (0.86, 0.99) | 0.91 (0.85, 0.97) | 0.91 (0.86, 0.97) |
| Nitrogen oxides | 1.12 (1.04, 1.21) | 1.23 (1.10, 1.38) | 1.09 (0.97, 1.23) | 1.14 (1.01, 1.28) | 1.20 (1.07, 1.34) |
| Nitrogen dioxide | 1.17 (1.09, 1.26) | 1.19 (1.08, 1.31) | 1.15 (1.04, 1.27) | 1.21 (1.09, 1.34) | 1.21 (1.11, 1.33) |
| Carbon monoxide | 1.07 (1.00, 1.15) | 1.15 (1.05, 1.26) | 1.06 (0.96, 1.16) | 1.09 (0.99, 1.20) | 1.14 (1.03, 1.27) |
| Fine particulates <2.5 microns | 1.09 (1.02, 1.16) | 1.07 (1.02, 1.13) | 1.05 (0.99, 1.11) | 1.03 (0.97, 1.09) | 1.03 (0.99, 1.08) |
| Particulates <10 microns | 1.12 (1.06, 1.19) | 1.13 (1.06, 1.21) | 1.10 (1.03, 1.18) | 1.08 (1.01, 1.15) | 1.10 (1.04, 1.17) |
| Small-for-gestational age <10th percentile | |||||
| Sulfur dioxide | 1.01 (0.97, 1.04) | 1.02 (0.99, 1.05) | 1.00 (0.97, 1.03) | 1.01 (0.98, 1.05) | 1.02 (0.99, 1.05) |
| Ozone | 0.95 (0.92, 0.98) | 0.96 (0.93, 0.98) | 0.98 (0.95, 1.01) | 0.97 (0.94, 1.00) | 0.95 (0.92, 0.97) |
| Nitrogen oxides | 1.00 (0.97, 1.04) | 1.02 (0.96, 1.08) | 0.97 (0.92, 1.03) | 1.00 (0.94, 1.06) | 1.08 (1.03, 1.14) |
| Nitrogen dioxide | 1.01 (0.97, 1.04) | 1.02 (0.98, 1.07) | 1.00 (0.95, 1.04) | 1.01 (0.96, 1.06) | 1.05 (1.01, 1.10) |
| Carbon monoxide | 0.99 (0.96, 1.02) | 1.01 (0.97, 1.06) | 0.97 (0.93, 1.01) | 0.99 (0.95, 1.04) | 1.05 (1.00, 1.10) |
| Fine particulates <2.5 microns | 1.01 (0.98, 1.04) | 1.00 (0.97, 1.02) | 1.01 (0.98, 1.04) | 0.99 (0.96, 1.02) | 1.02 (1.00, 1.05) |
| Particulates <10 microns | 1.02 (0.99, 1.05) | 1.01 (0.98, 1.05) | 1.01 (0.98, 1.05) | 1.00 (0.97, 1.04) | 1.03 (1.00, 1.06) |
RR, relative risk; CI, confidence interval
a
Fetal growth restriction was derived from medical records and/or International Classification of Diseases, Ninth Revision (ICD-9) codes; small-for-gestational age <10th percentile was defined as falling below the 10th percentile for birthweight standardized for gestational week and infant sex using a US population birthweight reference.
b
Models adjusted for maternal age, race/ethnicity, pre-pregnancy BMI, smoking, alcohol use, parity, insurance type, marital status, history of asthma and ambient temperature.