Table 4.
Interquartile increase in ambient air pollution and risk of 1) fetal growth restriction (FGR) without small-for-gestational age <10th percentile (SGA), 2) FGR with SGA, and 3) SGA without FGR, versus no SGA and no FGRb, by window of exposure.a
| 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) | |
|
FGR without SGA (n=713) |
|||||
| Sulfur dioxide | 1.25 (1.12, 1.39) | 1.25 (1.14, 1.37) | 1.20 (1.10, 1.32) | 1.17 (1.06, 1.30) | 1.22 (1.10, 1.34) |
| Ozone | 0.89 (0.80, 0.99) | 0.84 (0.77, 0.91) | 0.93 (0.84, 1.03) | 0.91 (0.83, 1.00) | 0.91 (0.83, 1.00) |
| Nitrogen oxides | 1.14 (1.02, 1.28) | 1.35 (1.14, 1.60) | 1.18 (0.98, 1.43) | 1.14 (0.94, 1.38) | 1.15 (0.97, 1.35) |
| Nitrogen dioxide | 1.21 (1.09, 1.35) | 1.37 (1.19, 1.57) | 1.23 (1.06, 1.44) | 1.24 (1.06, 1.44) | 1.23 (1.07, 1.40) |
| Carbon monoxide | 1.07 (0.97, 1.19) | 1.23 (1.07, 1.41) | 1.13 (0.98, 1.30) | 1.06 (0.91, 1.22) | 1.08 (0.93, 1.26) |
| Fine particulate matter <2.5 microns |
1.09 (0.99, 1.21) | 1.13 (1.03, 1.22) | 1.05 (0.95, 1.14) | 1.05 (0.96, 1.15) | 1.03 (0.95, 1.11) |
| Particulate matter <10 microns |
1.17 (1.07, 1.29) | 1.21 (1.09, 1.34) | 1.15 (1.04, 1.26) | 1.13 (1.02, 1.25) | 1.11 (1.02, 1.22 |
|
FGR with SGA (n=1018) |
|||||
| Sulfur dioxide | 1.10 (1.01, 1.21) | 1.10 (1.02, 1.18) | 1.05 (0.97, 1.14) | 1.10 (1.01, 1.20) | 1.13 (1.04, 1.22) |
| Ozone | 0.86 (0.78, 0.95) | 0.91 (0.84, 0.99) | 0.91 (0.83, 1.00) | 0.90 (0.83, 0.98) | 0.91 (0.84, 0.99) |
| Nitrogen oxides | 1.11 (1.01, 1.23) | 1.16 (0.99, 1.35) | 1.03 (0.88, 1.20) | 1.13 (0.97, 1.33) | 1.25 (1.07, 1.45) |
| Nitrogen dioxide | 1.14 (1.04, 1.26) | 1.08 (0.95, 1.22) | 1.09 (0.96, 1.24) | 1.20 (1.05, 1.37) | 1.21 (1.07, 1.36) |
| Carbon monoxide | 1.07 (0.98, 1.17) | 1.10 (0.97, 1.25) | 1.00 (0.89, 1.13) | 1.11 (0.98, 1.26) | 1.20 (1.05, 1.37) |
| Fine particulate matter <2.5 microns |
1.08 (0.99, 1.18) | 1.04 (0.97, 1.12) | 1.05 (0.97, 1.13) | 1.01 (0.93, 1.09) | 1.04 (0.98, 1.11) |
| Particulate matter <10 microns | 1.09 (1.01, 1.18) | 1.08 (0.99, 1.18) | 1.08 (0.99, 1.17) | 1.04 (0.95, 1.14) | 1.10 (1.02, 1.19) |
|
SGA without FGR (n=6791) |
|||||
| Sulfur dioxide | 0.99 (0.96, 1.03) | 1.01 (0.98, 1.05) | 0.99 (0.96, 1.02) | 1.00 (0.97, 1.04) | 1.01 (0.97, 1.04) |
| Ozone | 0.96 (0.92, 1.00) | 0.96 (0.93, 0.99) | 0.99 (0.95, 1.02) | 0.98 (0.95, 1.01) | 0.95 (0.92, 0.98) |
| Nitrogen oxides | 0.99 (0.95, 1.03) | 1.00 (0.95, 1.06) | 0.97 (0.91, 1.03) | 0.98 (0.92, 1.04) | 1.06 (1.01, 1.12) |
| Nitrogen dioxide | 0.99 (0.95, 1.03) | 1.02 (0.97, 1.07) | 0.98 (0.94, 1.04) | 0.99 (0.94, 1.04) | 1.03 (0.99, 1.08) |
| Carbon monoxide | 0.98 (0.95, 1.01) | 1.00 (0.95, 1.05) | 0.96 (0.92, 1.01) | 0.98 (0.93, 1.03) | 1.03 (0.98, 1.08) |
| Fine particulate matter <2.5 microns |
1.00 (0.97, 1.03) | 0.99 (0.96, 1.02) | 1.00 (0.97, 1.03) | 0.98 (0.96, 1.01) | 1.02 (1.00, 1.05) |
| Particulate matter <10 microns |
1.01 (0.98, 1.04) | 1.00 (0.97, 1.04) | 1.01 (0.97, 1.04) | 1.00 (0.97, 1.03) | 1.02 (0.99, 1.06) |
FGR, fetal growth restriction; SGA, small-for-gestational age; RR, relative risk; CI, confidence interval
Models adjusted for maternal age, race/ethnicity, pre-pregnancy BMI, smoking, alcohol use, parity, insurance type, marital status, history of asthma and ambient temperature.
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.