Association of PM_2.5 Exposure on Birthweight: Racial and Ethnic Disparities

Area of Science:

• Environmental Epidemiology
• Reproductive Health
• Air Pollution Toxicology

Background:

• Limited research exists on how fine particulate matter (PM2.5) affects birthweight across its distribution.
• Previous studies have yielded inconsistent findings and rarely examined racial/ethnic disparities or neighborhood composition impacts.

Purpose of the Study:

• To investigate racial/ethnic differences in the association between prenatal PM2.5 exposure and birthweight across the entire birthweight distribution.
• To assess how neighborhood racial/ethnic composition modifies these associations.

Main Methods:

• Retrospective cohort study of 102,986 singleton births in Harris County, Texas (2019-2020).
• PM2.5 exposure estimated using XGBoost-IDW Synthesis at the census tract level.
• Quantile regression models analyzed associations between PM2.5 and birthweight percentiles, with stratified analyses by maternal race/ethnicity and neighborhood composition.

Main Results:

• An inverted hook pattern was observed: PM2.5 was associated with reduced birthweight most strongly at the 10th and 90th percentiles.
• Weaker associations were noted at the 75th percentile.
• The strongest negative impact at the lowest percentile occurred in infants of Hispanic mothers or those in neighborhoods with less than a majority of non-Hispanic white residents.

Conclusions:

• Prenatal PM2.5 exposure is associated with reduced birthweight, with effects varying across the birthweight distribution.
• Significant disparities exist, with stronger associations observed based on maternal race/ethnicity and neighborhood racial/ethnic composition.