Ambient air pollution and low birth weight in Connecticut and Massachusetts.
BACKGROUND
Several studies have examined whether air pollution affects birth weight; however results vary and many studies were focused on Southern California or were conducted outside of the United States.


OBJECTIVE
We investigated maternal exposure to particulate matter with aerodynamic diameter < 10, < 2.5 microm (PM(10), PM(2.5)), sulfur dioxide, nitrogen dioxide, and carbon monoxide and birth weight for 358,504 births in Massachusetts and Connecticut from 1999 to 2002.


METHODS
Analysis included logistic models for low birth weight (< 2,500 g) and linear models with birth weight as a continuous variable. Exposure was assigned as the average county-level concentration over gestation and each trimester based on mother's residence. We adjusted for gestational length, prenatal care, type of delivery, child's sex, birth order, weather, year, and mother's race, education, marital status, age, and tobacco use.


RESULTS
An interquartile increase in gestational exposure to NO(2), CO, PM(10), and PM(2.5) lowered birth weight by 8.9 g [95% confidence interval (CI), 7.0-10.8], 16.2 g (95% CI, 12.6-19.7), 8.2 g (95% CI, 5.3-11.1), and 14.7 g (95% CI, 12.3-17.1), respectively. Lower birth weight was associated with exposure in the third trimester for PM(10), the first and third trimesters for CO, the first trimester for NO(2) and SO(2), and the second and third trimesters for PM(2.5). Effect estimates for PM(2.5) were higher for infants of black mothers than those of white mothers.


CONCLUSIONS
Results indicate that exposure to air pollution, even at low levels, may increase risk of low birth weight, particularly for some segments of the population.
Bell
Michelle L
ML
School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511, USA. michelle.bell@yale.edu
Ebisu
Keita
K
Belanger
Kathleen
K
D000397:Air Pollution; D002248:Carbon Monoxide / Q000633:toxicity; D003237:Connecticut; D005260:Female; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D008404:Massachusetts; D018811:Maternal Exposure; D009585:Nitrogen Dioxide / Q000633:toxicity; D010316:Particle Size; D011247:Pregnancy; D013458:Sulfur Dioxide / Q000633:toxicity
D013458:Sulfur Dioxide; D002248:Carbon Monoxide; D009585:Nitrogen Dioxide