title: Fetal exposure to maternal and paternal smoking and the risks of wheezing in preschool children: the Generation R Study.
abstract: BACKGROUND
  Previous studies have suggested that fetal smoke exposure is associated with increased risks of wheezing during childhood. The underlying pathways are unknown. We examined the associations of parental smoking during pregnancy with wheezing in preschool children and whether these associations are explained by postnatal smoke exposure or small for gestational age at birth.
  
  
  METHODS
  This study was embedded in a population-based prospective cohort study. Parental smoking was prospectively assessed by questionnaires. Wheezing was reported at 1 to 4 years. Small for gestational age at birth was available from registries. The analyses were based on 4,574 subjects.
  
  
  RESULTS
  Maternal smoking during the first trimester only was not associated with wheezing. Continued maternal smoking in pregnancy was associated with the risk of wheezing at 1 to 4 years (P for trends < .05). The strongest effect estimates were observed for frequent wheezing (four or more episodes of wheezing per year) until age 3 years (OR [95% CI]: age 1,1.64 [1.12-2.40]; age 2, 1.64 [1.01-2.64]; age 3, 2.19 [1.24-3.86]). Among children of nonsmoking mothers, fetal exposure to paternal smoking was not consistently associated with the risks of wheezing. The associations of continued maternal smoking during pregnancy with wheezing symptoms were independent of postnatal smoke exposure or small for gestational age at birth.
  
  
  CONCLUSIONS
  Fetal exposure to continued maternal smoking is associated with increased risks of wheezing in preschool children. Further research is needed to explore the effects of paternal smoking. Diminishing maternal smoking before conception or in early pregnancy is likely to have the greatest impact on reducing childhood wheezing.
authors.affiliation: Generation R Study Group, Department of Obstetrics and Gynaecology, Erasmus Medical Center, Rotterdam, The Netherlands; Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands; Division of Respiratory Medicine, Department of Pediatrics, Erasmus Medical Center, Rotterdam, The Netherlands; Department of Community Based Medicine, University of Bristol, Bristol, England. Electronic address: l.duijts@erasmusmc.nl.
authors.forename: Liesbeth
authors.initials: L
authors.lastname: Duijts
authors.affiliation: Generation R Study Group, Department of Obstetrics and Gynaecology, Erasmus Medical Center, Rotterdam, The Netherlands; Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands; Department of Pediatrics, Department of Obstetrics and Gynaecology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Vincent W V
authors.initials: VWV
authors.lastname: Jaddoe
authors.affiliation: Generation R Study Group, Department of Obstetrics and Gynaecology, Erasmus Medical Center, Rotterdam, The Netherlands; Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands; Division of Respiratory Medicine, Department of Pediatrics, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Ralf J P
authors.initials: RJP
authors.lastname: van der Valk
authors.affiliation: Department of Community Based Medicine, University of Bristol, Bristol, England.
authors.forename: John A
authors.initials: JA
authors.lastname: Henderson
authors.affiliation: Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Albert
authors.initials: A
authors.lastname: Hofman
authors.affiliation: Department of Public Health, Department of Obstetrics and Gynaecology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Hein
authors.initials: H
authors.lastname: Raat
authors.affiliation: Division of Obstetrics and Prenatal Medicine, Department of Obstetrics and Gynaecology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Eric A P
authors.initials: EAP
authors.lastname: Steegers
authors.affiliation: Department of Pediatrics, Department of Obstetrics and Gynaecology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Henriëtte A
authors.initials: HA
authors.lastname: Moll
authors.affiliation: Division of Respiratory Medicine, Department of Pediatrics, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Johan C
authors.initials: JC
authors.lastname: de Jongste
mesh_terms: D002675:Child, Preschool; D005220:Fathers; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D008297:Male; D009035:Mothers; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012135:Respiratory Sounds / Q000209:etiology*; D012907:Smoking; D014028:Tobacco Smoke Pollution
chemical_list: D014028:Tobacco Smoke Pollution