Prenatal fine particulate matter (PM₂.₅) exposure differentially impairs fetal skeletal and soft-tissue growth: a longitudinal study in rural Butajira, Ethiopia.

backgroundFetal growth is a key indicator of prenatal health and adverse perinatal outcomes. Maternal exposure to fine particulate matter (PM₂.₅) has been associated with impaired fetal development, yet evidence from low- and middle-income countries, particularly in rural high-exposure settings, remains limited. Few studies assessed repeated personal PM₂.₅ exposure measurements with longitudinal fetal growth trajectories. This study examined the association between personal maternal PM₂.₅ exposure and fetal growth trajectories in rural Butajira, Ethiopia.

methodsA community-based longitudinal study was conducted in rural Butajira, Ethiopia, from March to June, 2025. Pregnant women in early second trimester ( ≤ 24weeks) were recruited and followed at approximately 20, 30, and 36 weeks of gestation. Personal PM₂.₅ exposure was measured using Atmotube Pro air quality monitors over a 24-h period at each study visit, while fetal growth trajectories were measured by ultrasound. A linear mixed-effect model with random intercept was used to determine the association between PM₂.₅ exposure and fetal growth trajectories. Regression coefficient with 95% confidence interval was reported, and statistical significance was defined at p < 0.05. Covariates were selected based on prior knowledge and contexts.

resultsAn interquartile range (IQR; 27.0 µg/m³) increase in prenatal PM₂.₅ exposure was associated with a 0.43 standard deviation decrease in femur length (β = -0.43, 95%CI: -0.51, -0.35) and a 0.17 standard deviation decrease in abdominal circumference (β = -0.17, 95%CI: -0.21, -0.13). Similarly, lagged personal PM₂.₅ exposure showed comparable associations with these fetal growth trajectories. In contrast, no statistically significant association was observed for head circumference or biparietal diameter under either concurrent or lagged exposure. SIGNIFICANCE: This study provides longitudinal evidence that repeated personal PM₂.₅ exposure during pregnancy impairs fetal growth, particularly femur length and abdominal circumference. These findings highlight the need for integrating air pollution assessment into antenatal care and maternal health policies in low-resource settings. IMPACT: Prenatal PM₂.₅ exposure appears to selectively impair fetal skeletal and soft-tissue growth, highlighting a targeted vulnerability rather than uniform growth restriction. Integrating air pollution exposure assessment into antenatal care could enable earlier detection and intervention for environmentally driven growth impairments.