Particle air pollution and gestational diabetes mellitus in Houston, Texas

Background: There is mixed evidence implicating prenatal exposure to particulate matter <2.5 μm in aerodynamic diameter (PM_2.5) in the risk of gestational diabetes mellitus (GDM) and only one study has examined exposure to PM_2.5 constituents, which vary with location because of different emission sources.

Methods: We conducted a retrospective cohort study of singleton live births in Harris County, Texas from 2008 to 2013. With data from the Texas Commission on Environmental Quality (TCEQ), we spatially interpolated maternal exposures to total and speciated PM_2.5, nitrogen dioxide (NO₂) and ozone (O₃) over the 12-week preconception period and trimesters 1 and 2. We estimated odds ratios (OR) and 95% confidence intervals (CI) for the association between pre-conception and pregnancy exposures to total and speciated PM_2.5 and odds of GDM, adjusted for temperature and maternal covariates. We also evaluated confounding from NO₂ and O₃ exposures in multi-pollutant models.

Results: An interquartile range (IQR) increase in total PM_2.5 exposure was associated with elevated odds for developing GDM over the preconception (adjusted OR = 1.09, 95% CI: 1.06, 1.12), first trimester (OR = 1.13, 95% CI: 1.10, 1.17) and second trimester (OR = 1.13, 95% CI: 1.09, 1.17) periods. Effect estimates increased with adjustment for NO₂ and O₃. We observed modest increases in odds of GDM for IQR increases in first trimester ammonium ion PM_2.5 (OR = 1.03, 95% CI: 1.00, 1.05) and sulfate PM_2.5 (OR = 1.03, 95% CI: 1.00, 1.05) exposures, as well as preconception Cr PM_2.5 exposures (OR = 1.05, 95% CI: 1.02, 1.07).

Conclusion: Exposures to PM_2.5, before and during pregnancy were associated with elevated odds of GDM. Mitigating air pollution exposures may reduce the risk of GDM and its long-term implications for maternal and child health.