Impact of ambient air pollution on birth weight in Sydney, Australia.
BACKGROUND
Studies in Asia, Europe, and the Americas have provided evidence that ambient air pollution may have an adverse effect on birth weight, although results are not consistent.


METHODS
Average exposure during pregnancy to five common air pollutants was estimated for births in metropolitan Sydney between 1998 and 2000. The effects of pollutant exposure in the first, second, and third trimesters of pregnancy on risk of "small for gestational age" (SGA), and of pollutant exposure during pregnancy on birth weight were examined.


RESULTS
There were 138,056 singleton births in Sydney between 1998 and 2000; 9.7% of babies (13,402) were classified as SGA. Air pollution levels in Sydney were found to be quite low. In linear regression models carbon monoxide and nitrogen dioxide concentrations in the second and third trimesters had a statistically significant adverse effect on birth weight. For a 1 part per million increase in mean carbon monoxide levels a reduction of 7 (95% CI -5 to 19) to 29 (95% CI 7 to 51) grams in birth weight was estimated. For a 1 part per billion increase in mean nitrogen dioxide levels a reduction of 1 (95% CI 0 to 2) to 34 (95% CI 24 to 43) grams in birth weight was estimated. Particulate matter (diameter less than ten microns) in the second trimester had a small statistically significant adverse effect on birth weight. For a 1 microgram per cubic metre increase in mean particulate matter levels a reduction of 4 grams (95% CI 3 to 6) in birth weight was estimated.


CONCLUSIONS
These findings of an association between carbon monoxide, nitrogen dioxide, and particulate matter, and reduction in birth weight should be corroborated by further study.
Mannes
T
T
NSW Public Health Officer Training Program, New South Wales Health Department, North Sydney, Australia. paman@doh.health.nsw.gov.au
Jalaludin
B
B
Morgan
G
G
Lincoln
D
D
Sheppeard
V
V
Corbett
S
S
D000393:Air Pollutants / Q000032:analysis / Q000633:toxicity*; D001724:Birth Weight; D002245:Carbon Dioxide / Q000032:analysis / Q000633:toxicity*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D008297:Male; D008423:Maternal Age; D018811:Maternal Exposure / Q000009:adverse effects*; D009517:New South Wales / Q000453:epidemiology; D009585:Nitrogen Dioxide / Q000032:analysis / Q000633:toxicity*; D011247:Pregnancy; D012044:Regression Analysis
D000393:Air Pollutants; D002245:Carbon Dioxide; D009585:Nitrogen Dioxide