Particulate matter 2.5 exposure during pregnancy and birth outcomes: Evidence from Colombia

Particulate matter is a type of air pollution that consists of fine particles with a diameter <2.5 μm (PM_2.5), which can easily penetrate the respiratory system and enter the bloodstream, increasing health risks for pregnant women and their unborn babies. Recent reports have suggested that there is a positive association between PM_2.5 exposure and adverse pregnancy outcomes. However, most evidence of this relationship comes from Western countries. Thus, the objective of this study was to evaluate the association between PM_2.5 exposure during pregnancy and birth outcomes among pregnant women in Colombia. This study included 542,800 singletons born in 2019 to Colombian women, aged 15+ years, residing in 981 municipalities. Data on parental, child and birth characteristics were extracted from anonymized live birth records. Satellite-based estimates of monthly PM_2.5 concentrations at the surface level were extracted for each municipality from the Atmospheric Composition Analysis Group (ACAG). PM_2.5 exposure during pregnancy was indicated by the monthly average of PM_2.5 concentrations across the pregnancy duration for the municipality where the child was born. The associations of municipality-level PM_2.5 concentration during pregnancy with pre-term birth (PTB) and low birth weight (LBW) were tested in separate two-level logistic regression models, with babies nested within municipalities. The prevalence of PTB and LBW were 8.6 % and 8.3 %, respectively. The mean PM_2.5 concentration across the 981 municipalities was 18.26 ± 3.30 μg/m³, ranging from 9.11 to 31.44 μg/m³. Greater PM_2.5 concentration at municipality level was associated with greater odds of PTB (1.05; 95%CI: 1.04-1.06) and LBW (1.04; 95%CI: 1.03-1.05), after adjustment for confounders. Our findings provide new evidence on the association between PM_2.5 on adverse pregnancy outcomes from a middle-income country.