Trimester-Specific Prenatal Exposure to PM2.5 and Birth Weight among Minority Populations in Puerto Rico

摘要

Background: While prenatal exposure to air pollutants has been associated with adverse birth outcomes, these associations are largely unstudied in minority populations. We assessed the association between trimester-specific maternal exposure to fine particulate matter (PM2.5) and birthweight (BW) in Puerto Rico for live births between 1999 and 2013. Methods: We studied 339,805 singleton births (mean gestational age: 37.9 weeks, SD: 2.9) to mothers whose mean age was 25.2 years (SD 6.0) in 37 Puerto Rican municipalities with at least 50% of their land area within 10 miles of a central regulatory air pollution monitor, from which we obtained daily PM2.5 concentrations. We included births for which gestational age was ≥20 weeks. PM2.5 exposure data were available for ≥75% of days in each trimester. We used a Poisson regression model with a sandwich linearized estimator of variance to estimate the association between mean exposure levels per trimester and BW, dichotomized as less than or ≥2,500 grams. We adjusted for individual and municipal-level confounders and allowed for potential clustering by municipality. Results: Median PM2.5 concentration across the study period was 7.0 micrograms/m3 [interquartile range (IQR) 6.0-8.1], and 35,751 infants (10.5%) had low BW. Mothers attended ≥10 prenatal visits for 69.8% of births, 89.1% of them were Hispanic and 10.9% were black. The risk ratios associated with an IQR difference in PM2.5 concentration were 1.00 (95% CI 0.98,1.02), 1.02 (1.00, 1.04), and 1.00 (0.98,1.03) for trimesters 1, 2, and 3, respectively. Sensitivity analysis using ordinal logistic models that cast BW as very low, low, and normal yielded similar results: odds ratios 1.00 (0.98, 1.02), 1.02 (0.99,1.04), and 1.01 (0.98, 1.04) for respective trimesters. Conclusion: Over 14 years in a population exposed to relatively low levels of PM2.5, second trimester exposures had the strongest association with low birth weight.