Association of Atmospheric Particulate Matter and Ozone With Gestational Diabetes Mellitus

Hui Hu; Sandie Ha; Barron H. Henderson; Tamara D. Warner; Jeffrey Roth; Haidong Kan; Xiaohui Xu

Disclosures

Environ Health Perspect. 2015;123(9):853-859. 

In This Article

Abstract and Introduction

Abstract

Background: Ambient air pollution has been linked to the development of gestational diabetes mellitus (GDM). However, evidence of the association is very limited, and no study has estimated the effects of ozone.

Objective: Our aim was to determine the association of prenatal exposures to particulate matter ≤ 2.5 μm (PM2.5) and ozone (O3) with GDM.

Methods: We used Florida birth vital statistics records to investigate the association between the risk of GDM and two air pollutants (PM2.5 and O3) among 410,267 women who gave birth in Florida between 2004 and 2005. Individual air pollution exposure was assessed at the woman's home address at time of delivery using the hierarchical Bayesian space–time statistical model. We further estimated associations between air pollution exposures during different trimesters and GDM.

Results: After controlling for nine covariates, we observed increased odds of GDM with per 5-μg/m3 increase in PM2.5 (ORTrimester1 = 1.16; 95% CI: 1.11, 1.21; ORTrimester2 = 1.15; 95% CI: 1.10, 1.20; ORPregnancy = 1.20; 95% CI: 1.13, 1.26) and per 5-ppb increase in O3 (ORTrimester1 = 1.09; 95% CI: 1.07, 1.11; ORTrimester2 = 1.12; 95% CI: 1.10, 1.14; ORPregnancy = 1.18; 95% CI: 1.15, 1.21) during both the first trimester and second trimester as well as the full pregnancy in single-pollutant models. Compared with the single-pollutant model, the ORs for O3 were almost identical in the co-pollutant model. However, the ORs for PM2.5 during the first trimester and the full pregnancy were attenuated, and no association was observed for PM2.5 during the second trimester in the co-pollutant model (OR = 1.02; 95% CI: 0.98, 1.07).

Conclusion: This population-based study suggests that exposure to air pollution during pregnancy is associated with increased risk of GDM in Florida, USA.

Introduction

Gestational diabetes mellitus (GDM) is a common complication during pregnancy. It is defined as any degree of glucose intolerance with onset or first recognition during pregnancy (American Diabetes Association 2013). GDM complicates up to 14% of all pregnancies depending on the populations observed. More than 200,000 cases were reported annually in the United States (American Diabetes Association 2013). GDM has adverse effects on both the mother and the developing fetus. About one-third of women with GDM will eventually develop type 2 diabetes (Linné et al. 2002), and women with GDM also have higher long-term risks of cardiovascular diseases compared with those without GDM (Kitzmiller et al. 2007). In children, GDM has been associated with both perinatal and long-term adverse health outcomes such as macrosomia (Hughes et al. 1997), shoulder dystocia (Athukorala et al. 2007), birth injuries (Mitanchez 2010), sustained glucose tolerance impairment (Silverman et al. 1995), obesity (Pettitt et al. 1985), and impaired intellectual abilities (Rizzo et al. 1997). GDM has also been associated with metabolic disturbances in offspring of mothers with GDM (Boerschmann et al. 2010; Clausen et al. 2008; Lawlor et al. 2011), and the prevalence of type 2 diabetes or pre-diabetes at 18–27 years of age was almost eight times higher among offspring of women with GDM compared with other children in a case–control study (Clausen et al. 2008). Although previous studies have shown that treatment of GDM can reduce serious perinatal morbidity such as macrosomia at birth (Crowther et al. 2005), a recent study found no significant difference in body mass index (BMI) z-scores or BMI ≥ 85th percentile in children at 4–5 years of age whose mothers were treated for GDM (n = 94) compared with children whose mothers had GDM but received only routine care (n = 105) (Gillman et al. 2010). However, the sample size of this study was relatively small and may be underpowered.

Despite great improvements in air quality following the Clean Air Act (1963), air pollution remains a significant public health problem in the United States. According to the State of the Air 2013 report by the American Lung Association (2013), 41% of the population in the United States still lives in counties that have unhealthy levels of air pollution. Evidence on the effects of air pollution on diabetes mellitus in the general population has been reported in several recent epidemiological studies. A study of the Danish Diet, Cancer and Health cohort reported that traffic-related air pollution, using nitrogen dioxide (NO2) as a proxy, was associated with higher mortality from diabetes (Raaschou-Nielsen et al. 2013). Two studies in North America reported positive associations of NO2 and PM2.5 (particulate matter with diameter ≤ 2.5 μm) with the prevalence of diabetes (Brook et al. 2008; Pearson et al. 2010). In addition, positive associations have been found between air pollution and insulin resistance, the pathological hallmark underlying diabetes (Andersen et al. 2012; Chuang et al. 2011; Coogan et al. 2012; Kelishadi et al. 2009; Kim and Hong 2012; Krämer et al. 2010; Puett et al. 2011; Sun et al. 2013).

Although the biological mechanisms leading to GDM are still unclear, it is plausible that air pollution during pregnancy may increase the risk of GDM by inducing oxidative stress, and consequently inflammation, insulin resistance, dyslipidemia, and systemic metabolic dysfunction (Andersen et al. 2012; Chuang et al. 2011; Coogan et al. 2012; Everett et al. 2010; Hotamisligil et al. 1993; Kelishadi et al. 2009; Kim and Hong 2012; Krämer et al. 2010; Lamb and Goldstein 2008; Puett et al. 2011; Sun Y et al. 2006; Sun Z et al. 2013). Although evidence of adverse effects of air pollution on birth defects and pregnancy complications such as gestational hypertension has been widely reported in the last decade (Šrám et al. 2005; Xu et al. 2014), studies focusing on the association between ambient air pollution and GDM are still very limited. To our knowledge, only three previous studies have investigated air pollution and GDM. Malmqvist et al. (2013) reported a positive association between NOx exposure and GDM, whereas an earlier study by van den Hooven et al. (2009) reported no association. A recent study found that exposure to PM2.5 and other traffic-related pollutants during pregnancy has been associated with impaired glucose tolerance but not GDM in women from Boston, Massachusetts, USA (Fleisch et al. 2014). Given the inconclusive results and limited types of pollutants examined in previous studies, investigation of the association between GDM and other criteria air pollutants such as ozone (O3) is warranted. In this study, we analyzed Florida birth vital statistics records for 410,267 women who gave birth during 2004–2005, to examine the association between the risk of GDM and two ambient air pollutants, PM2.5 and O3, assessed using the hierarchical Bayesian space–time statistical model (HBM) developed by the U.S. Environmental Protection Agency (EPA) and the Centers for Disease Control and Prevention's (CDC) National Environmental Public Health Tracking Network (U.S. EPA 2014). We also investigated whether associations between exposure to air pollution and GDM varied among different gestational periods (trimesters and full pregnancy).

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