title: A time series analysis of outdoor air pollution and preterm birth in Shanghai, China.
abstract: OBJECTIVE
  To investigate the relation between air pollution exposure and preterm birth in Shanghai, China.
  
  
  METHODS
  We examined the effect of ambient air pollution on preterm birth using time-series approach in Shanghai in 2004. This method can eliminate potential confounding by individual risk factors that do not change over a short period of time. Daily numbers of preterm births were obtained from the live birth database maintained by Shanghai Municipal Center of Disease Control and Prevention. We used the generalized additive model (GAM) with penalized splines to analyze the relation between preterm birth, air pollution, and covariates.
  
  
  RESULTS
  We observed a significant effect of outdoor air pollution only with 8-week exposure before preterm births. An increase of 10 microg/m3 of 8-week average PM10, SO2, NO2, and O3 corresponded to 4.42% (95%CI 1.60%, 7.25%), 11.89% (95%CI 6.69%, 17.09%), 5.43% (95%CI 1.78%, 9.08%), and 4.63% (95%CI 0.35%, 8.91%) increase of preterm birth. We did not find any significant acute effect of outdoor air pollution on preterm birth in the week before birth.
  
  
  CONCLUSIONS
  Ambient air pollution may contribute to the risk of preterm birth in Shanghai. Our analyses also strengthen the rationale for further limiting air pollution level in the city.
authors.affiliation: Shanghai Municipal Center of Disease Control and Prevention, Shanghai 200336, China.
authors.forename: Li-Li
authors.initials: LL
authors.lastname: Jiang
authors.forename: Yun-Hui
authors.initials: YH
authors.lastname: Zhang
authors.forename: Gui-Xiang
authors.initials: GX
authors.lastname: Song
authors.forename: Guo-Hai
authors.initials: GH
authors.lastname: Chen
authors.forename: Bing-Heng
authors.initials: BH
authors.lastname: Chen
authors.forename: Nai-Qing
authors.initials: NQ
authors.lastname: Zhao
authors.forename: Hai-Dong
authors.initials: HD
authors.lastname: Kan
mesh_terms: D000393:Air Pollutants / Q000009:adverse effects*; D000397:Air Pollution / Q000009:adverse effects*; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology / Q000209:etiology*
chemical_list: D000393:Air Pollutants