Intrauterine inflammation and maternal exposure to ambient [PM.sub.2.5] during preconception and specific periods of pregnancy: the Boston birth cohort

BACKGROUND: Prenatal exposure to ambient [PM.sub.2.5], (i.e., fine particulate matter, aerodynamic diameter ≤ 2.5 µm) has been associated with preterm birth and low birth weight. The association between prenatal [PM.sub.2.5] exposure and intrauterine inflammation (IUI), an important risk factor for preterm birth and neurodevelopmental outcomes, has not been evaluated. OBJECTIVES: We aimed to investigate the association between maternal exposure to [PM.sub.2.5] and IUI in the Boston Birth Cohort, a predominantly urban low-income minority population. METHODS: This analysis included 5,059 mother-infant pairs in the Boston Birth Cohort. IUI was assessed based on intrapartum fever and placenta pathology. [PM.sub.2.5] exposure was assigned using data from the U.S. EPA's Air Quality System. Odds ratios (OR) and 95% confidence intervals (CI) quantified the association of maternal [PM.sub.2.5] exposure during preconception and various periods of pregnancy with IUI. RESULTS: Comparing the highest with the lowest [PM.sub.2.5] exposure quartiles, the multi-adjusted association with IUI was significant for all exposure periods considered, including 3 months before conception (OR = 1.52; 95% CI: 1.22, 1.89), first trimester (OR = 1.93; 95% CI: 1.55, 2.40), second trimester (OR = 1.67; 95% CI: 1.35, 2.08), third trimester (OR = 1.53; 95% CI: 1.24, 1.90), and whole pregnancy (OR = 1.92; 95% CI: 1.55, 2.37). CONCLUSIONS: Despite relatively low exposures, our results suggest a monotonic positive relationship between [PM.sub.2.5] exposure during preconception and pregnancy and IUI. IUI may be a sensitive biomarker for assessing early biological effect of [PM.sub.2.5] exposure on the developing fetus. http://dx.doi.org/10.1289/EHP243
Introduction Maternal exposure to air pollution during pregnancy is associated with adverse birth outcomes such as low birth weight and preterm birth (Bell et al. 2007; Brauer et al. 2008; [...]