title: Does fetal smoke exposure affect childhood bone mass? The Generation R Study.
abstract: We assessed the intrauterine influence of maternal smoking on childhood bone mass by comparing parental prenatal and postnatal smoking habits. We observed higher bone mass in children exposed to maternal smoking, explained by higher body weight. Maternal smoking or related lifestyle factors may affect childhood weight gain rather than skeletal growth.
  
  
  BACKGROUND
  Maternal smoking during pregnancy may adversely affect bone health in later life. By comparing the associations of maternal and paternal smoking and of prenatal and postnatal exposure with childhood bone measures, we aimed to explore whether the suggested association could be explained by fetal programming or reflects confounding by familial factors.
  
  
  METHODS
  In 5565 mothers, fathers and children participating in a population-based prospective cohort study, parental smoking habits during pregnancy and current household smoking habits were assessed by postal questionnaires. Total body bone mineral content (BMC), bone area (BA) and bone mineral density (BMD) were measured by dual-energy X-ray absorptiometry (DXA) at the median age of 6.0 years (IQR 0.37).
  
  
  RESULTS
  In confounder-adjusted models, maternal smoking during pregnancy was associated with a higher BMC of 11.6 g (95 % confidence interval (CI) 5.6, 17.5), a larger BA of 9.7 cm(2) (95 % CI 3.0, 16.4), a higher BMD of 6.7 g/cm(2) (95 % CI 2.4, 11.0) and a higher BMC of 5.4 g (95 % CI 1.3, 9.6) adjusted for BA of the child. Current weight turned out to mediate these associations. Among mothers who did not smoke, paternal smoking did not show evident associations with childhood bone measures. Also, household smoking practices during childhood were not associated with childhood bone measures.
  
  
  CONCLUSIONS
  Our results do not support the hypothesis of fetal smoke exposure affecting childhood bone mass via intrauterine mechanisms. Maternal smoking or related lifestyle factors may affect childhood weight gain rather than skeletal growth.
authors.affiliation: The Generation R Study Group, Erasmus Medical Center, Room Ae-012, PO Box 2040, 3000 CA, Rotterdam, The Netherlands.
authors.forename: D H M
authors.initials: DH
authors.lastname: Heppe
authors.forename: C
authors.initials: C
authors.lastname: Medina-Gomez
authors.forename: A
authors.initials: A
authors.lastname: Hofman
authors.forename: F
authors.initials: F
authors.lastname: Rivadeneira
authors.forename: V W V
authors.initials: VW
authors.lastname: Jaddoe
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D001835:Body Weight / Q000502:physiology; D015519:Bone Density / Q000502:physiology*; D002648:Child; D005220:Fathers / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D009035:Mothers / Q000523:psychology; D009426:Netherlands / Q000453:epidemiology; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology / Q000503:physiopathology*; D011446:Prospective Studies; D012907:Smoking / Q000453:epidemiology; D012959:Socioeconomic Factors; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D014028:Tobacco Smoke Pollution