Wildfire-specific fine particulate matter and preterm birth: a US ECHO Cohort analysis

Area of Science:

• Environmental Health
• Reproductive Epidemiology
• Public Health

Background:

• Prenatal exposure to fine particulate matter (PM2.5) from wildfire smoke is a potential risk factor for preterm birth.
• The US Environmental Influences on Child Health Outcomes (ECHO) Cohort provides a nationwide dataset to investigate this association.

Purpose of the Study:

• To examine the relationship between prenatal wildfire PM2.5 exposure and preterm birth.
• To assess the impact of wildfire smoke exposure intensity, duration, and timing on preterm birth risk.

Main Methods:

• Analysis of live singleton births within the ECHO Cohort (2006-2020).
• Linking census tract-level wildfire PM2.5 estimates to residential histories.
• Calculating metrics of exposure: mean concentration, smoke days, and smoke waves.
• Using logistic regression to analyze associations with preterm birth, stratified by region (nationwide vs. US West).

Main Results:

• In the US West sample, increased odds of preterm birth were associated with higher mean daily wildfire PM2.5, more smoke days (≥5.0 and ≥10.0 μg/m³), and longer smoke waves (≥4 days).
• Nationwide, preterm birth was linked to smoke days in mid-pregnancy (PM2.5 >0, ≥2.5, ≥5.0 μg/m³) and late pregnancy (PM2.5 ≥10.0 μg/m³).
• An exposure-response relationship was observed in the western US, with increasing intensity and duration of exposure linked to higher preterm birth odds.

Conclusions:

• Wildfire PM2.5 exposure during pregnancy is associated with increased odds of preterm birth, especially in the western United States.
• Findings suggest a dose-response relationship between wildfire smoke exposure and preterm birth.
• Public health interventions are needed to mitigate prenatal exposure to wildfire smoke.