Does ambient air pollution trigger stillbirth?

Epidemiology. 2013 Jul;24(4):538-44. doi: 10.1097/EDE.0b013e3182949ce5.


Objective: We previously reported an increased risk of stillbirth associated with increases in trimester-specific ambient air pollutant concentrations. Here, we consider whether sudden increase in the mean ambient air pollutant concentration immediately before delivery triggers stillbirth.

Methods: We used New Jersey linked fetal death and hospital discharge data and hourly ambient air pollution measurements from particulate matter ≤ 2.5 mm (PM2.5), carbon monoxide (CO), nitrogen dioxide (NO2), and sulfur dioxide (SO2) monitors across New Jersey for the years 1998-2004. For each stillbirth, we assigned the concentration of air pollutants from the closest monitoring site within 10 km of the maternal residence. Using a time-stratified case-crossover design and conditional logistic regression, we estimated the relative odds of stillbirth associated with interquartile range (IQR) increases in the mean pollutant concentrations on lag day 2 and lag days 2 through 6 before delivery, and whether these associations were modified by maternal risk factors.

Results: The relative odds of stillbirth increased with IQR increases in the mean concentrations of CO (odds ratio [OR] = 1.20, 95% confidence interval [CI] = 1.05-1.37), SO2 (OR = 1.11, 95% CI = 1.02-1.22), NO2 (OR = 1.11, 95% CI = 0.97-1.26), and PM2.5 (OR = 1.07, 95% CI = 0.93-1.22) 2 days before delivery. We found similar associations with increases in pollutants 2 through 6 days before delivery. These associations were not modified by maternal risk factors.

Conclusion: Short-term increases in ambient air pollutant concentrations immediately before delivery may trigger stillbirth.

MeSH terms

  • Adult
  • Air Pollutants / adverse effects*
  • Air Pollution / adverse effects*
  • Carbon Monoxide / adverse effects
  • Female
  • Humans
  • New Jersey / epidemiology
  • Nitrogen Dioxide / adverse effects
  • Particulate Matter / adverse effects
  • Pregnancy
  • Risk Assessment
  • Risk Factors
  • Stillbirth / epidemiology*
  • Sulfur Dioxide / adverse effects
  • Time Factors


  • Air Pollutants
  • Particulate Matter
  • Sulfur Dioxide
  • Carbon Monoxide
  • Nitrogen Dioxide