Differences in Birth Weight Associated with the 2008 Beijing Olympics Air Pollution Reduction: Results from a Natural Experiment.
BACKGROUND
Previous studies have reported decreased birth weight associated with increased air pollutant concentrations during pregnancy. However, it is not clear when during pregnancy increases in air pollution are associated with the largest differences in birth weight.


OBJECTIVE
Using the natural experiment of air pollution declines during the 2008 Beijing Olympics, we evaluated whether having specific months of pregnancy (i.e., 1st…8th) during the 2008 Olympics period was associated with larger birth weights, compared with pregnancies during the same dates in 2007 or 2009.


METHODS
Using n = 83,672 term births to mothers residing in four urban districts of Beijing, we estimated the difference in birth weight associated with having individual months of pregnancy during the 2008 Olympics (8 August-24 September 2008) compared with the same dates in 2007 and 2009. We also estimated the difference in birth weight associated with interquartile range (IQR) increases in mean ambient particulate matter ≤ 2.5 μm in aerodynamic diameter (PM2.5), sulfur dioxide (SO2), nitrogen dioxide (NO2), and carbon monoxide (CO) concentrations during each pregnancy month.


RESULTS
Babies whose 8th month of gestation occurred during the 2008 Olympics were, on average, 23 g larger (95% CI: 5 g, 40 g) than babies whose 8th month occurred during the same calendar dates in 2007 or 2009. IQR increases in PM2.5 (19.8 μg/m3), CO (0.3 ppm), SO2 (1.8 ppb), and NO2 (13.6 ppb) concentrations during the 8th month of pregnancy were associated with 18 g (95% CI: -32 g, -3 g), 17 g (95% CI: -28 g, -6 g), 23 g (95% CI: -36 g, -10 g), and 34 g (95% CI: -70 g, 3 g) decreases in birth weight, respectively. We did not see significant associations for months 1-7.


CONCLUSIONS
Short-term decreases in air pollution late in pregnancy in Beijing during the 2008 Summer Olympics, a normally heavily polluted city, were associated with higher birth weight.


BACKGROUND
Rich DQ, Liu K, Zhang J, Thurston SW, Stevens TP, Pan Y, Kane C, Weinberger B, Ohman-Strickland P, Woodruff TJ, Duan X, Assibey-Mensah V, Zhang J. 2015. Differences in birth weight associated with the 2008 Beijing Olympics air pollution reduction: results from a natural experiment. Environ Health Perspect 123:880-887; http://dx.doi.org/10.1289/ehp.1408795.
Department of Public Health Sciences, School of Medicine and Dentistry, University of Rochester, Rochester, New York, USA.
David Q
DQ
Rich
Kaibo
K
Liu
Jinliang
J
Zhang
Sally W
SW
Thurston
Timothy P
TP
Stevens
Ying
Y
Pan
Cathleen
C
Kane
Barry
B
Weinberger
Pamela
P
Ohman-Strickland
Tracey J
TJ
Woodruff
Xiaoli
X
Duan
Vanessa
V
Assibey-Mensah
Junfeng
J
Zhang
D000393:Air Pollutants / Q000009:adverse effects*; D000397:Air Pollution / Q000009:adverse effects*; D000068476:Beijing / Q000453:epidemiology; D001724:Birth Weight; D002248:Carbon Monoxide / Q000633:toxicity; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D018811:Maternal Exposure / Q000009:adverse effects; D009585:Nitrogen Dioxide / Q000633:toxicity; D052638:Particulate Matter / Q000633:toxicity; D011247:Pregnancy; D013458:Sulfur Dioxide / Q000009:adverse effects
D000393:Air Pollutants; D052638:Particulate Matter; D013458:Sulfur Dioxide; D002248:Carbon Monoxide; D009585:Nitrogen Dioxide