title: Birth weight and subsequent risk of asthma: a systematic review and meta-analysis.
abstract: BACKGROUND
  Previous studies suggest that birth weight is related to later risk of asthma. However, few meta-analyses have investigated these associations. Therefore, we performed a meta-analysis with different classifications to further validate the relationship between birth weight and asthma.
  
  
  METHODS
  PubMed (1990-2013), ScienceDirect (1990-2013), EMBASE(1990-2013),EBSCO (1990-2013) and Springer (1990-2013) were searched for articles. The following MeSH terms were used: "birth weight", "fetal growth retardation", "intrauterine growth restriction", "asthma", "wheezing".
  
  
  RESULTS
  We included 18 studies with data from a total of over 90,000 children and adults. (1) Low birth weight (<2,500g) as compared with BW>2,500g and BW=2500-4000g was associated with increased risk of asthma (Children: OR, 1.28; 95% CI, 1.09-1.50, P<0.05; OR, 1.34; 95% CI, 1.13-1.60, P<0.05, Adults: OR, 1.25; 95% CI, 1.12-1.39, P<0.05; OR, 1.25; 95% CI, 1.12-1.40, P<0.05). (2) High birth weight (>4,000g) was not associated with the risk of asthma when BW<4,000g and BW=2500-4000g were used as the reference.
  
  
  CONCLUSIONS
  These results suggest that low birth weight (<2,500g) is associated with increased risk of asthma both in children and adults and may serve as a mediator between prenatal influences and later disease risk; but high birth weight (>4,000g) was not associated with increased risk of asthma.
authors.affiliation: Department of Public Health, School of Medicine, Anhui University of Science and Technology, People's Republic of China. Electronic address: mumin0611@sina.com.
authors.forename: Min
authors.initials: M
authors.lastname: Mu
authors.affiliation: Department of Public Health, School of Medicine, Anhui University of Science and Technology, People's Republic of China. Electronic address: candymu@126.com.
authors.forename: Song
authors.initials: S
authors.lastname: Ye
authors.affiliation: Department of Public Health, School of Medicine, Anhui University of Science and Technology, People's Republic of China. Electronic address: mingjiebai@126.com.
authors.forename: Ming-Jie
authors.initials: MJ
authors.lastname: Bai
authors.affiliation: Department of Public Health, School of Medicine, Anhui University of Science and Technology, People's Republic of China.
authors.forename: Guo-Li
authors.initials: GL
authors.lastname: Liu
authors.affiliation: Department of Public Health, School of Medicine, Anhui University of Science and Technology, People's Republic of China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Tong
authors.affiliation: Department of Nutrition, School of Public Health, Anhui Medical University, People's Republic of China; Department of University Hospital, Anhui Medical University, People's Republic of China. Electronic address: candymu@126.com.
authors.forename: Su-Fang
authors.initials: SF
authors.lastname: Wang
authors.affiliation: Department of Nutrition, School of Public Health, Anhui Medical University, People's Republic of China; Department of University Hospital, Anhui Medical University, People's Republic of China. Electronic address: jieshengmm@126.com.
authors.forename: Jie
authors.initials: J
authors.lastname: Sheng
mesh_terms: D000328:Adult; D001249:Asthma / Q000209:etiology*; D001724:Birth Weight; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D008297:Male; D012307:Risk Factors
keywords: Asthma; Birth weight; Foetal growth; Meta-analysis; Respiratory symptoms