title: [Ambient PM2.5 during pregnancy and risk on preterm birth].
abstract: OBJECTIVE
  To investigate the association between ambient fine particulate matter with aerodynamic diameter less than 2.5 μm (PM2.5) and the risk on preterm birth.
  
  
  METHODS
  A total of 1 882 pregnant women with local residency of Taiyuan city and underwent delivery at the First Hospital of Shanxi Medical University with the dates of conception between January 1 and December 31, 2013, were enrolled in the study. Information on general demographics, home address and history on pregnancy, lifestyle and related environmental factors were collected through in-person interview. Birth outcomes and maternal complications were abstracted from medical records. Data on the amount of daily average PM2.5 from 8 monitor points in Taiyuan city, between March 1, 2012 and December 31, 2013 were also collected. Individual exposure during pregnancy were calculated using the inverse-distance weighting method, based on home address. Multivariate unconditional logistic regression model was used to examine the associations among PM2.5 exposure, risk of preterm birth and related clinical subtypes.
  
  
  RESULTS
  The overall incidence of preterm birth was 8.21% (151/1 839)in 1 839 pregnant women. Exposure to ambient PM2.5 during the second week prior to delivery was associated with an increased risk of preterm birth (OR=1.087, 95% CI: 1.001-1.182 per 10 μg/m(3) increase) and mild preterm birth (OR=1.099, 95% CI: 1.007-1.200 per 10 μg/m(3)). Compared to data from the China Environmental Air Quality Standard, higher level of exposure (≥75 μg/m(3)) of PM2.5 during the second week before delivery was associated with an increased risk of preterm birth (OR=1.008, 95%CI: 1.000-1.017) but the association was mainly seen for mild preterm birth (OR=1.010, 95%CI: 1.001-1.018).
  
  
  CONCLUSIONS
  RESULTS from our study showed that exposure to high level of PM2.5 during late pregnancy would increase the risk of preterm birth. Future large studies are needed to examine the association by preterm clinical subtypes and to elucidate potential underlying mechanisms.
authors.affiliation: Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan 030001, China.
authors.forename: Yanpeng
authors.initials: Y
authors.lastname: Cheng
authors.affiliation: Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan 030001, China.
authors.forename: Yongliang
authors.initials: Y
authors.lastname: Feng
authors.affiliation: State Key Lab of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Duan
authors.affiliation: Division of Environmental Health Sciences, School of Public Health, Yale University.
authors.forename: Nan
authors.initials: N
authors.lastname: Zhao
authors.affiliation: Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan 030001, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan 030001, China.
authors.forename: Chunxia
authors.initials: C
authors.lastname: Li
authors.affiliation: Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan 030001, China.
authors.forename: Pengge
authors.initials: P
authors.lastname: Guo
authors.affiliation: Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan 030001, China.
authors.forename: Bingjie
authors.initials: B
authors.lastname: Xie
authors.affiliation: Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan 030001, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Zhang
authors.affiliation: Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan 030001, China.
authors.forename: Haixiu
authors.initials: H
authors.lastname: Wen
authors.affiliation: Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan 030001, China.
authors.forename: Mei
authors.initials: M
authors.lastname: Li
authors.affiliation: Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan 030001, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan 030001, China.
authors.forename: Suping
authors.initials: S
authors.lastname: Wang
authors.affiliation: Division of Environmental Health Sciences, School of Public Health, Yale University.
authors.forename: Yawei
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D002681:China / Q000453:epidemiology; D004781:Environmental Exposure / Q000009:adverse effects* / Q000032:analysis; D005260:Female; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D016015:Logistic Models; D018811:Maternal Exposure; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis / Q000633:toxicity*; D011247:Pregnancy; D011248:Pregnancy Complications; D047928:Premature Birth / Q000139:chemically induced* / Q000453:epidemiology*; D011634:Public Health / Q000706:statistics & numerical data*
chemical_list: D052638:Particulate Matter