title: Does ambient air pollution trigger stillbirth?
abstract: 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.
  
  
  CONCLUSIONS
  Short-term increases in ambient air pollutant concentrations immediately before delivery may trigger stillbirth.
authors.affiliation: University of Medicine and Dentistry New Jersey-Robert Wood Johnson Medical School, New Brunswick, NJ 08903, USA. faizas@umdnj.edu
authors.forename: Ambarina S
authors.initials: AS
authors.lastname: Faiz
authors.forename: George G
authors.initials: GG
authors.lastname: Rhoads
authors.forename: Kitaw
authors.initials: K
authors.lastname: Demissie
authors.forename: Yong
authors.initials: Y
authors.lastname: Lin
authors.forename: Lakota
authors.initials: L
authors.lastname: Kruse
authors.forename: David Q
authors.initials: DQ
authors.lastname: Rich
mesh_terms: D000328:Adult; D000393:Air Pollutants / Q000009:adverse effects*; D000397:Air Pollution / Q000009:adverse effects*; D002248:Carbon Monoxide / Q000009:adverse effects; D005260:Female; D006801:Humans; D009515:New Jersey / Q000453:epidemiology; D009585:Nitrogen Dioxide / Q000009:adverse effects; D052638:Particulate Matter / Q000009:adverse effects; D011247:Pregnancy; D018570:Risk Assessment; D012307:Risk Factors; D050497:Stillbirth / Q000453:epidemiology*; D013458:Sulfur Dioxide / Q000009:adverse effects; D013997:Time Factors
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D013458:Sulfur Dioxide; D002248:Carbon Monoxide; D009585:Nitrogen Dioxide