title: Exposure to ambient air pollution during pregnancy and preterm birth: A Spanish multicenter birth cohort study.
abstract: OBJECTIVE
  Preterm birth is a major determinant of infant mortality and morbidity. Air pollution has been suggested as a risk factor for preterm delivery; however, the scientific evidence on this impact remains inconsistent. We assessed the association between residential exposure to air pollution during pregnancy and preterm birth (gestational age at delivery <37 weeks) in Spain.
  
  
  METHODS
  This study was based on 2409 pregnant women participating in the INMA birth cohorts in Asturias, Gipuzkoa, Sabadell and Valencia. Ambient levels of nitrogen dioxide (NO2) and benzene were estimated for each woman's residence for each trimester and for the whole pregnancy, using temporally adjusted land-use regression models. The association between air pollution exposure and preterm birth was assessed for each cohort separately by means of logistic regression models controlling for potential confounders, under single- and two-pollutant models, for all the women in the study and for those spending more than 15h/day at home. Combined estimates of the association across cohorts were obtained through meta-analysis.
  
  
  RESULTS
  Throughout the whole sample, suggestive but no statistically significant associations were found between exposure and preterm birth. For pregnant women spending more time at home significant associations were found for both pollutants, under single- and two-pollutant models. Under the last ones, NO2 exposure during the second trimester and the whole pregnancy was associated with a higher risk of preterm delivery (OR=1.58, (95%CI: 1.04-2.42) per 10μg/m(3) increase). Benzene exposure during the third trimester was also associated with preterm birth in that subsample (OR=1.45, (95%CI: 1.00-2.09) per 1μg/m(3) increase).
  
  
  CONCLUSIONS
  We found suggestive associations between NO2 and benzene exposure during pregnancy and preterm birth. Estimates of the association were higher among women who spent more time at home, probably reflecting a better exposure assessment in this group.
authors: Epidemiology and Environmental Health Joint Research Unit, FISABIO-Universitat Jaume I-Universitat de València, Avenida de Catalunya 21, 46020 Valencia, Spain; Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain.
authors: Marisa
authors: M
authors: Estarlich
authors: Epidemiology and Environmental Health Joint Research Unit, FISABIO-Universitat Jaume I-Universitat de València, Avenida de Catalunya 21, 46020 Valencia, Spain; Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain. Electronic address: ballester_fer@gva.es.
authors: Ferran
authors: F
authors: Ballester
authors: Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain; Center for Research in Environmental Epidemiology (CREAL), Barcelona, Catalonia, Spain; Experimental and Health Sciences, Pompeu Fabra University, 08003 Barcelona, Catalonia, Spain.
authors: Payam
authors: P
authors: Davdand
authors: Epidemiology and Environmental Health Joint Research Unit, FISABIO-Universitat Jaume I-Universitat de València, Avenida de Catalunya 21, 46020 Valencia, Spain; Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain.
authors: Sabrina
authors: S
authors: Llop
authors: Epidemiology and Environmental Health Joint Research Unit, FISABIO-Universitat Jaume I-Universitat de València, Avenida de Catalunya 21, 46020 Valencia, Spain; Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain.
authors: Ana
authors: A
authors: Esplugues
authors: Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain; University of Oviedo, Oviedo, Spain.
authors: Ana
authors: A
authors: Fernández-Somoano
authors: Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain; University of the Basque Country, EHU/UPV, Spain; Health Research Institute (BIODONOSTIA), Spain.
authors: Aitana
authors: A
authors: Lertxundi
authors: Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain; Center for Research in Environmental Epidemiology (CREAL), Barcelona, Catalonia, Spain; Experimental and Health Sciences, Pompeu Fabra University, 08003 Barcelona, Catalonia, Spain; Department of Child and Adolescent Psychiatry/Psychology, Erasmus University Medical Centre-Sophia Children's Hospital, Rotterdam, The Netherlands.
authors: Mònica
authors: M
authors: Guxens
authors: Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain; Public Health Division of Gipuzkoa, Basque Government, San Sebastián, Spain; Health Research Institute (BIODONOSTIA), Spain.
authors: Mikel
authors: M
authors: Basterrechea
authors: Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain; University of Oviedo, Oviedo, Spain.
authors: Adonina
authors: A
authors: Tardón
authors: Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain; Center for Research in Environmental Epidemiology (CREAL), Barcelona, Catalonia, Spain; Experimental and Health Sciences, Pompeu Fabra University, 08003 Barcelona, Catalonia, Spain.
authors: Jordi
authors: J
authors: Sunyer
authors: Epidemiology and Environmental Health Joint Research Unit, FISABIO-Universitat Jaume I-Universitat de València, Avenida de Catalunya 21, 46020 Valencia, Spain; Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain.
authors: Carmen
authors: C
authors: Iñiguez
mesh_terms: D000293:Adolescent; D000328:Adult; D000393:Air Pollutants / Q000032:analysis / Q000633:toxicity*; D001554:Benzene / Q000032:analysis / Q000633:toxicity*; D015331:Cohort Studies; D004784:Environmental Monitoring; D005260:Female; D006801:Humans; D016015:Logistic Models; D018811:Maternal Exposure; D009585:Nitrogen Dioxide / Q000032:analysis / Q000633:toxicity*; D011247:Pregnancy; D047928:Premature Birth / Q000139:chemically induced / Q000453:epidemiology*; D012111:Residence Characteristics; D012307:Risk Factors; D012959:Socioeconomic Factors; D013030:Spain / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000393:Air Pollutants; D001554:Benzene; D009585:Nitrogen Dioxide
keywords: Air pollution; Cohort; Pregnancy; Preterm birth