| Pollutant (n) | Interquartile range | Trimester of mean concentration | SGA* | VSGA† |
| Fine particles: PM2.5 (n = 88,678) | 4 μg/m3 | First trimester | 4.5 (0.5 to 8.7) | 2.6 (−4.4 to 10.0) |
| Second trimester | −1.8 (−5.6 to 2.2) | 0.2 (−6.7 to 7.5) | ||
| Third trimester | 4.1 (0.3 to 8.0) | 4.2 (−2.4 to 11.2) | ||
| Sulphur dioxide (n = 132,888) | 3 ppb | First trimester | 1.7 (−0.9 to 4.3) | 0.0 (−4.6 to 4.8) |
| Second trimester | 0.2 (−2.4 to 2.9) | 2.5 (−2.2 to 7.4) | ||
| Third trimester | −0.1 (−2.8 to 2.6) | 3.1 (−1.8 to 8.3) | ||
| Nitrogen dioxide (n = 114,411) | 10 ppb | First trimester | 1.2 (−1.6 to 4.0) | 7.0 (1.8 to 12.4) |
| Second trimester | 1.1 (−1.6 to 3.9) | 7.7 (2.6 to 13.0) | ||
| Third trimester | 1.0 (−1.7 to 3.7) | 7.4 (2.5 to 12.5) | ||
| Carbon monoxide (n = 134,798) | 0.5 ppm | First trimester | 1.1 (−2.0 to 4.3) | −4.1 (−9.4 to 1.4) |
| Second trimester | 0.0 (−3.0 to 3.1) | −1.9 (−7.1 to 3.6) | ||
| Third trimester | 0.1 (−2.8 to 3.1) | 1.1 (−4.1 to 6.5) |
New Jersey Air Pollution and Adverse Birth Outcomes Study, 1999–2003.
*SGA, “small for gestational age” defined as a fetal growth ratio (ie, newborn’s birthweight divided by median birthweight of corresponding gestational age/gender/race-specific stratum) ⩾0.75 and <0.85.
†VSGA, “very small for gestational age” defined as fetal growth ratio <0.75.
Note: Each trimester-specific pollutant concentration was modelled separately. All risk estimates adjusted for maternal race/ethnicity, maternal education, maternal age, marital status, trimester prenatal care began, maternal alcohol use, maternal smoking, maternal drug use, percentage of population (⩾25 years) in maternal residence census tract with <12 years of education, percentage of population (⩾25 years) in maternal residence census tract with at least 4 years of college, and percentage of population in maternal residence census tract below federally defined poverty line.