title: Exposure to ambient air pollutants and spontaneous abortion.
abstract: OBJECTIVE
  This study aimed to evaluate the correlation between ambient concentrations of air pollutants and first-trimester spontaneous abortion.
  
  
  METHODS
  This was a retrospective case–control study, which was conducted on 296 women from June 2010 to February 2011 in Tehran, Iran. Cases were 148 women who experienced a spontaneous abortion before 14 weeks of gestation while the controls were 148 pregnant women after 14 weeks of gestation and groups were matched on sociodemographics and obstetrics characteristics. The samples were recruited randomly from 10 hospitals. In total, pollutants concentrations were collected at 29 stations hourly throughout the study area. We estimated the mean exposure for each participant and investigated the association between spontaneous abortion and ambient pollutants.
  
  
  RESULTS
  Findings demonstrated that the average of ambient air pollutants in the cases was significantly higher than in the controls (P < 0.05). The odd ratios of abortion in the areas with higher concentrations of CO, NO₂, O₃ and PM₁₀ were 1.98, 0.96, 0.94 and 1.01, respectively (P < 0.05). Also, the model showed that there was no significant association between prenatal exposures to SO₂ and abortion (P > 0.05).
  
  
  CONCLUSIONS
  Our findings suggest that pregnant women exposed to ambient air pollutants may be at increased risk of spontaneous abortion. Confirmation by further research is needed.
authors.forename: Maryam
authors.initials: M
authors.lastname: Moridi
authors.forename: Saeideh
authors.initials: S
authors.lastname: Ziaei
authors.forename: Anoshirvan
authors.initials: A
authors.lastname: Kazemnejad
mesh_terms: D000022:Abortion, Spontaneous / Q000139:chemically induced* / Q000453:epidemiology; D000393:Air Pollutants / Q000633:toxicity*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D019570:Inhalation Exposure / Q000009:adverse effects*; D007492:Iran / Q000453:epidemiology; D008954:Models, Biological; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012189:Retrospective Studies; D012306:Risk
chemical_list: D000393:Air Pollutants