title: Sex-specific differences in fetal growth in newborns exposed prenatally to traffic-related air pollution in the PELAGIE mother-child cohort (Brittany, France).
abstract: BACKGROUND
  Numerous studies have linked prenatal traffic-related air pollution exposure to fetal growth. Recently, several studies have suggested exploring this association independently among boys and girls because of potential sex-specific biological vulnerability to air pollution. Residence-based factors can also influence fetal growth by enhancing susceptibility to the toxic effects of air pollution and must also be considered in these relations.
  
  
  OBJECTIVE
  We examined sex-specific associations between prenatal air pollution exposure and fetal growth and explored whether they differed by the urban-rural status of maternal residence.
  
  
  METHODS
  This study relied on the PELAGIE mother-child cohort (2521 women, Brittany, France, 2002-2006). Fetal growth was assessed through birth weight, head circumference and small weight (SGA) and small head circumference (SHC) for gestational age. Nitrogen dioxide (NO2) concentrations at mothers' homes were estimated by using a land use regression model taking into account temporal variation during pregnancy. Associations between estimated NO2 concentrations and fetal growth were assessed with linear regression or logistic regression models, depending on the outcome investigated.
  
  
  RESULTS
  An interquartile range (8.8 µg m(-3)) increase in NO2 exposure estimates was associated with a 27.4 g (95% CI 0.8 to 55.6) increase in birth weight and a 0.09 cm (95% CI 0.00-0.17) significant increase in head circumference, among newborn boys only. Their risks of SGA and SHC were reduced (OR 0.70, 95% CI 0.53-0.92, OR 0.76, 95% CI 0.56-1.03, respectively, for an increase of 8.8 µg m(-3)). No statistically significant trends were observed among girls. Urban-rural status modified the effect of air pollution only for SHC and again only for newborn boys.
  
  
  CONCLUSIONS
  Findings from this study confirm the need to consider sex-specific associations between air pollution and fetal growth and to investigate possible mechanisms by which traffic-related air pollution may increase anthropometric parameters at birth.
authors.affiliation: INSERM U1085-IRSET, France; University of Rennes 1, Rennes, France; EHESP School of Public Health, Sorbone Paris Cité, Rennes, France.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Bertin
authors.affiliation: INSERM U1085-IRSET, France; University of Rennes 1, Rennes, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Chevrier
authors.affiliation: INSERM U1085-IRSET, France; University of Rennes 1, Rennes, France; EHESP School of Public Health, Sorbone Paris Cité, Rennes, France.
authors.forename: Tania
authors.initials: T
authors.lastname: Serrano
authors.affiliation: INSERM U1085-IRSET, France; University of Rennes 1, Rennes, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Monfort
authors.affiliation: INSERM U1085-IRSET, France; University of Rennes 1, Rennes, France.
authors.forename: Sylvaine
authors.initials: S
authors.lastname: Cordier
authors.affiliation: INSERM U1085-IRSET, France; University of Rennes 1, Rennes, France; Department of Epidemiology and Public Health, University Hospital, 2 rue Henri Le Guilloux, 35033 Rennes, France. Electronic address: jean-francois.viel@univ-rennes1.fr.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Viel
mesh_terms: D000328:Adult; D000393:Air Pollutants / Q000633:toxicity*; D015331:Cohort Studies; D005260:Female; D047109:Fetal Development; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012737:Sex Factors; D001335:Vehicle Emissions
chemical_list: D000393:Air Pollutants; D001335:Vehicle Emissions
keywords: Air pollution; Birth weight; Child sex; Head circumference; Urban–rural context