Ambient Air Pollution and Risk of Gestational Hypertension

Abstract

Air pollution has been linked to hypertension in the general population, but data on gestational hypertension (GH) are limited. We investigated criteria air pollutants and air toxics during the period before conception and in early gestation in relation to GH risk in the Consortium on Safe Labor/Air Quality and Reproductive Health Study (United States, 2002-2008). Modified Community Multi-scale Air Quality models estimated air pollution exposures for 6,074 singleton pregnancies in which GH was present and 199,980 normotensive pregnancies. Generalized estimating equations estimated relative risks per interquartile-range increment for pollutants and high exposure (≥75th percentile) for air toxics after adjustment for major risk factors. For an interquartile-range increment, GH risk was significantly increased by 18% for sulfur dioxide during the 3 months before conception and, during gestational weeks 1-20, 17% for nitrogen oxides, 10% for particulate matter with an aerodynamic diameter <2.5 μm, 7% for particulate matter with an aerodynamic diameter <10 μm, and 22% for sulfur dioxide. High exposures to several polycyclic aromatic hydrocarbons before conception and during the first trimester were significantly associated with 8%-20% higher risk of GH. Further, preconceptional exposures to several volatile organic compounds were significantly associated with 11%-19% higher risk. Our findings suggest that early exposures to criteria air pollutants, particularly from transport emissions, and high exposure to several air toxics before conception may increase GH risk.

Keywords: ambient air pollution; gestational hypertension; polycyclic aromatic hydrocarbons; volatile organic compounds.

Figure 1.

Adjusted relative risks (RRs) for gestational hypertension associated with an interquartile-range increment of exposure to criteria air pollutants and constituents of particulate matter with aerodynamic diameter ≤2.5 μm (PM_2.5) during 3 months before conception (A, B), gestational weeks 1–13 (C, D), and gestational weeks 1–20 (E, F), Consortium on Safe Labor/Air Quality and Reproductive Health Study, United States, 2002–2008. The models adjusted for study site, maternal age, race/ethnicity, marital status, insurance, parity, prepregnancy body mass index, preexisting chronic disease, smoking during pregnancy, alcohol consumption during pregnancy, and season of conception. AP, ammonium particles; CO, carbon monoxide; DP, dust particles; EC, elemental carbon; NO_x, nitrogen oxides; NP, nitrate particles; O₃, ozone; OC, organic compounds; PM₁₀, particulate matter with aerodynamic diameter ≤10 μm; SO₂, sulfur dioxide; SP, sulfite particles. Bars, 95% confidence intervals.