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Differences in Birth Weight Associated with the 2008 Beijing Olympics Air Pollution Reduction: Results from a Natural Experiment.

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 - Environ. Health Perspect. (2015)

Bottom Line: We did not see significant associations for months 1-7.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.Differences in birth weight associated with the 2008 Beijing Olympics air pollution reduction: results from a natural experiment.

View Article: PubMed Central - PubMed

Affiliation: Department of Public Health Sciences, School of Medicine and Dentistry, University of Rochester, Rochester, New York, USA.

ABSTRACT

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.

Objectives: 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.

Citation: 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.

No MeSH data available.


Related in: MedlinePlus

Plots of sorted birth weight residuals for births with the 8th month of pregnancy from 8 August to 24 September versus sorted expected values from a normal distribution with the same mean and variance (Q-Q plots) in (A) 2007, (B) 2008, or (C) 2009.
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f2: Plots of sorted birth weight residuals for births with the 8th month of pregnancy from 8 August to 24 September versus sorted expected values from a normal distribution with the same mean and variance (Q-Q plots) in (A) 2007, (B) 2008, or (C) 2009.

Mentions: We next evaluated whether our 8th month finding was limited to pregnancies with one or more complications (i.e., either a pregnancy-related hypertensive disorder or a fetal placental condition), or to small or large birth weight babies. When excluding the 2.0% (n = 189) of pregnancies with a pregnancy-related hypertensive disorder and then the 12.9% (n = 1,204) of pregnancies with a fetal placental condition, having the 8th month of pregnancy during the 2008 Olympics period instead of the same dates in 2007 or 2009 was still associated with significant 24-g (95% CI: 7 g, 42 g) and 22-g (95% CI: 4 g, 37 g) increases in birth weight, respectively. Further, Q-Q plots revealed similar patterns of residuals in the upper and lower ends of the birth weight distribution across all 3 years (Figure 2). Thus, our reported increase in birth weight for pregnancies with their 8th month of pregnancy during the Olympics period (23 g), compared with the same dates in 2007 or 2009 described above, does not appear to be driven by differences in the low or high end of the birth weight distribution. We observed increases in birth weight associated with the 8th month of pregnancy occurring during the 2008 Olympics period, compared with the same dates in 2007 and 2009, among pregnant women living in Xicheng (20 g; 95% CI: –46 g, 86 g), Haidan (41 g; 95% CI: 10 g, 71 g), and Chaoyang (32 g; 95% CI: 4 g, 59 g) districts, but not in Fengtai (–18 g; 95% CI: –57 g, 19 g). Last, we observed increases in birth weight associated with the 8th month of pregnancy occurring during the 2008 Olympics period, compared with the same dates in 2007 and 2009, for all maternal education levels (bachelor’s degree or more: 29 g, 95% CI: 5 g, 52 g; technical school: 22 g, 95% CI: –9 g, 52 g; high school or less: 5 g; 95% CI: –40 g, 50 g), although the largest difference was observed among those with a bachelor’s degree or more.


Differences in Birth Weight Associated with the 2008 Beijing Olympics Air Pollution Reduction: Results from a Natural Experiment.

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 - Environ. Health Perspect. (2015)

Plots of sorted birth weight residuals for births with the 8th month of pregnancy from 8 August to 24 September versus sorted expected values from a normal distribution with the same mean and variance (Q-Q plots) in (A) 2007, (B) 2008, or (C) 2009.
© Copyright Policy - public-domain
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4559955&req=5

f2: Plots of sorted birth weight residuals for births with the 8th month of pregnancy from 8 August to 24 September versus sorted expected values from a normal distribution with the same mean and variance (Q-Q plots) in (A) 2007, (B) 2008, or (C) 2009.
Mentions: We next evaluated whether our 8th month finding was limited to pregnancies with one or more complications (i.e., either a pregnancy-related hypertensive disorder or a fetal placental condition), or to small or large birth weight babies. When excluding the 2.0% (n = 189) of pregnancies with a pregnancy-related hypertensive disorder and then the 12.9% (n = 1,204) of pregnancies with a fetal placental condition, having the 8th month of pregnancy during the 2008 Olympics period instead of the same dates in 2007 or 2009 was still associated with significant 24-g (95% CI: 7 g, 42 g) and 22-g (95% CI: 4 g, 37 g) increases in birth weight, respectively. Further, Q-Q plots revealed similar patterns of residuals in the upper and lower ends of the birth weight distribution across all 3 years (Figure 2). Thus, our reported increase in birth weight for pregnancies with their 8th month of pregnancy during the Olympics period (23 g), compared with the same dates in 2007 or 2009 described above, does not appear to be driven by differences in the low or high end of the birth weight distribution. We observed increases in birth weight associated with the 8th month of pregnancy occurring during the 2008 Olympics period, compared with the same dates in 2007 and 2009, among pregnant women living in Xicheng (20 g; 95% CI: –46 g, 86 g), Haidan (41 g; 95% CI: 10 g, 71 g), and Chaoyang (32 g; 95% CI: 4 g, 59 g) districts, but not in Fengtai (–18 g; 95% CI: –57 g, 19 g). Last, we observed increases in birth weight associated with the 8th month of pregnancy occurring during the 2008 Olympics period, compared with the same dates in 2007 and 2009, for all maternal education levels (bachelor’s degree or more: 29 g, 95% CI: 5 g, 52 g; technical school: 22 g, 95% CI: –9 g, 52 g; high school or less: 5 g; 95% CI: –40 g, 50 g), although the largest difference was observed among those with a bachelor’s degree or more.

Bottom Line: We did not see significant associations for months 1-7.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.Differences in birth weight associated with the 2008 Beijing Olympics air pollution reduction: results from a natural experiment.

View Article: PubMed Central - PubMed

Affiliation: Department of Public Health Sciences, School of Medicine and Dentistry, University of Rochester, Rochester, New York, USA.

ABSTRACT

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.

Objectives: 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.

Citation: 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.

No MeSH data available.


Related in: MedlinePlus