Ambient Air Pollution and Preterm Birth in the Environment and Pregnancy Outcomes Study at the University of California, Los Angeles

Abstract

The authors conducted a case-control survey nested within a birth cohort and collected detailed risk factor information to assess the extent to which residual confounding and exposure misclassification may impact air pollution effect estimates. Using a survey of 2,543 of 6,374 women sampled from a cohort of 58,316 eligible births in 2003 in Los Angeles County, California, the authors estimated with logistic regression and two-phase models the effects of pregnancy period-specific air pollution exposure on the odds of preterm birth. For the first trimester, the odds of preterm birth consistently increased with increasing carbon monoxide exposures and also at high levels of exposure to particulate matter less than or equal to 2.5 microm in diameter (>21.4 microg/m(3)), regardless of type of data (cohort/sample) or covariate adjustment (carbon monoxide exposures of >1.25 ppm increased the odds by 21-25%). Women exposed to carbon monoxide above 0.91 ppm during the last 6 weeks of pregnancy experienced increased odds of preterm birth. Crude and birth certificate covariate-adjusted results for carbon monoxide differed from each other. However, further adjustment for risk factors assessed in the survey did not change effect estimates for short-term pollutant averages appreciably, except for time-activity patterns, which strengthened the observed associations. These results confirm the importance of reducing exposure misclassification when evaluating the effect of traffic-related pollutants that vary spatially.

Impact of short-term preconceptional exposure to particulate air pollution on treatment outcome in couples undergoing in vitro fertilization and embryo transfer (IVF/ET)

“…Over the past few years an increasing amount of evidence derived from studies focused particularly on male fertility and pregnancy outcome showed the negative effects of environmental contaminants derived from traffic emissions, including ozone (O3), CO, SOx, NOx, benzene, formaldehyde, PAHs, and suspended PM present in urban air on human reproductive health [9][10][11][12][13][14]. In contrast, few studies were able to demonstrate an association between air pollution and fertility impairment in women, probably due to the multiplicity of factors involved in female reproductive function [15][16][17].…”

Air Pollution and Adverse Pregnancy Outcome

“…The association of NO 2 exposure and PTB was explored in 10 studies (Bobak, 2000;Gehring et al, 2011;Jalaludin et al, 2007;Leem et al, 2006;Liu et al, 2003;Llop et al 2010;Maroziene and Grazuleviciene, 2002;Ritz et al,2000Ritz et al, , 2007Ritz et al, , 2011 (Table 2). Bobak (2000) (first and third trimester), Maroziene and Grazuleviciene(2002) (first trimester), Leem et al (2006), Bobak (2000) (first and third trimester), Llop et al (2010) (second and third trimester and entire pregnancy) reported an increased risk of PTB; however, others reported no association.…”

“…Bobak (2000) (first and third trimester), Maroziene and Grazuleviciene(2002) (first trimester), Leem et al (2006), Bobak (2000) (first and third trimester), Llop et al (2010) (second and third trimester and entire pregnancy) reported an increased risk of PTB; however, others reported no association. The association between CO exposure and preterm birth was explored in 6 studies (Ritz et al, 2000;Huynh et al, 2006;Leem et al, 2006;Liu et al, 2003;Wilhelm and Ritz, 2005;Ritz et al, 2007). Liu et al (2003) (last month of the pregnancy), Wilhelm and Ritz (2005) (first trimester), leem et al (2006) (first and third trimester) and Ritz et al (2007) (first trimester) reported a higher risk of PTB with higher concentration of CO. 4 of 6 studies reported a higher risk of PTB with CO exposure around 1ppm.…”

“…The association between CO exposure and preterm birth was explored in 6 studies (Ritz et al, 2000;Huynh et al, 2006;Leem et al, 2006;Liu et al, 2003;Wilhelm and Ritz, 2005;Ritz et al, 2007). Liu et al (2003) (last month of the pregnancy), Wilhelm and Ritz (2005) (first trimester), leem et al (2006) (first and third trimester) and Ritz et al (2007) (first trimester) reported a higher risk of PTB with higher concentration of CO. 4 of 6 studies reported a higher risk of PTB with CO exposure around 1ppm. In particular, Leem et al's study (2006) showed that the relationships between PTB and exposures to CO was dose dependent (p<0.001).…”

“…But Ritz et al(2000) and Huynh et al (2006) did not report the association between CO exposure and preterm birth There was a significant dose-dependent association between gestational age and sulfur dioxide and total suspended particulate concentrations ( Xu et al, 1995). In 3 studies (Ritz et al, 2000;Liu et al, 2003;Ritz et al, 2007, the association between exposure to ozone and PTB was investigated (Table 2). None of these studies reported a statistically significant increase in PTB with higher exposure to ozone.…”