title: Evaluation of the association between maternal smoking, childhood obesity, and metabolic disorders: a national toxicology program workshop review.
abstract: BACKGROUND
  An emerging literature suggests that environmental chemicals may play a role in the development of childhood obesity and metabolic disorders, especially when exposure occurs early in life.
  
  
  OBJECTIVE
  Here we assess the association between these health outcomes and exposure to maternal smoking during pregnancy as part of a broader effort to develop a research agenda to better understand the role of environmental chemicals as potential risk factors for obesity and metabolic disorders.
  
  
  METHODS
  PubMed was searched up to 8 March 2012 for epidemiological and experimental animal studies related to maternal smoking or nicotine exposure during pregnancy and childhood obesity or metabolic disorders at any age. A total of 101 studies-83 in humans and 18 in animals-were identified as the primary literature.
  
  
  CONCLUSIONS
  Current epidemiological data support a positive association between maternal smoking and increased risk of obesity or overweight in offspring. The data strongly suggest a causal relation, although the possibility that the association is attributable to unmeasured residual confounding cannot be completely ruled out. This conclusion is supported by findings from laboratory animals exposed to nicotine during development. The existing literature on human exposures does not support an association between maternal smoking during pregnancy and type 1 diabetes in offspring. Too few human studies have assessed outcomes related to type 2 diabetes or metabolic syndrome to reach conclusions based on patterns of findings. There may be a number of mechanistic pathways important for the development of aberrant metabolic outcomes following perinatal exposure to cigarette smoke, which remain largely unexplored.
  
  
  CONCLUSIONS
  From a toxicological perspective, the linkages between maternal smoking during pregnancy and childhood overweight/obesity provide proof-of-concept of how early-life exposure to an environmental toxicant can be a risk factor for childhood obesity.
authors.affiliation: Kelly Government Solutions, Research Triangle Park, North Carolina, USA.
authors.forename: Mamta
authors.initials: M
authors.lastname: Behl
authors.forename: Deepa
authors.initials: D
authors.lastname: Rao
authors.forename: Kjersti
authors.initials: K
authors.lastname: Aagaard
authors.forename: Terry L
authors.initials: TL
authors.lastname: Davidson
authors.forename: Edward D
authors.initials: ED
authors.lastname: Levin
authors.forename: Theodore A
authors.initials: TA
authors.lastname: Slotkin
authors.forename: Supriya
authors.initials: S
authors.lastname: Srinivasan
authors.forename: David
authors.initials: D
authors.lastname: Wallinga
authors.forename: Morris F
authors.initials: MF
authors.lastname: White
authors.forename: Vickie R
authors.initials: VR
authors.lastname: Walker
authors.forename: Kristina A
authors.initials: KA
authors.lastname: Thayer
authors.forename: Alison C
authors.initials: AC
authors.lastname: Holloway
mesh_terms: D000818:Animals; D002648:Child; D015986:Confounding Factors, Epidemiologic; D004785:Environmental Pollutants / Q000633:toxicity*; D005260:Female; D006801:Humans; D008659:Metabolic Diseases / Q000150:complications*; D009538:Nicotine / Q000008:administration & dosage; D009765:Obesity / Q000150:complications*; D011247:Pregnancy; D012307:Risk Factors; D012907:Smoking
chemical_list: D004785:Environmental Pollutants; D009538:Nicotine