Air pollution and birth weight in northern Nevada, 1991-1999

This study examined the association between particulate matter <10 mu m in aerodynamic size (PM10), carbon monoxide (CO), and ozone (O-3), and birth weight in Washoe County, NV, from 1991 through 1999. In total, 39, 338 single births were included in this study. The mean birth weight was 3383 +/- 460 g and prevalence of low birth weight (LBW) was 2.46% for single births with a gestational age of 37-44 wk. After controlling for cofactors including infant sex, maternal residential city, education, medical risk factors, active tobacco use, drug use, alcohol use, prenatal care, mother's age, race and ethnicity of mothers, and weight gain of mothers, we found PM10 exposure in the third trimester of pregnancy to be a significant predictor of birth weight of newborns. A 10-mu g/m(3) increase in the 24-h PM10 level in the third trimester of pregnancy can be associated with a birth-weight reduction of 11 g (95% CI: 2.3-19.8 g) using multiple linear regression; however, PM10 was not found to be related with the risk of LBW from logistic regression. CO and O-3 were not found to be associated with birth weight or risk of LBW of newborns by the same modeling procedure. The results suggest PM10 could be a risk factor associated with birth-weight reduction of newborns in urban northern Nevada; however, the current level of PM10 is not a risk factor to increase the chance of LBW newborns.