title: Preterm birth and low birth weight continue to increase the risk of asthma from age 7 to 43.
abstract: BACKGROUND
  Perinatal events can influence the development of asthma in childhood but current evidence is contradictory concerning the effects on life-time asthma risk.
  
  
  OBJECTIVE
  To assess the relationship between birth characteristics and asthma from childhood to adulthood.
  
  
  METHODS
  All available birth records for the Tasmanian Longitudinal Health Study (TAHS) cohort, born in 1961 were obtained from the Tasmanian State Archives and Tasmanian hospitals. Low birth weight (LBW) was defined as less than 2500 grams. Preterm birth was defined as delivery before 37 weeks' gestation. Small for gestational age (SGA) was defined as a birth weight below the 10thpercentile for a given gestational age. Multivariate logistic and cox regression were used to examine associations between birth characteristics and lifetime risk of current and incident asthma, adjusting for confounders.
  
  
  RESULTS
  The prevalence of LBW was 5.2%, SGA was 13.8% and preterm was 3.3%. LBW (OR = 1.65, 95%CI 1.12,2.44) and preterm birth (OR = 1.81, 95%CI 0.99, 3.31) were both associated with an increased risk of current asthma between the ages of 7 to 43 years. There was no association between SGA and current asthma risk. However, SGA was associated with incident asthma (HR = 1.32, 95%CI 1.00, 1.74), and there was an interaction with sex (p value = 0.08), with males having a greater risk of incident asthma (HR = 1.70, 95%CI 1.16-2.49) than females (HR = 1.04, 95%CI 0.70-1.54).
  
  
  CONCLUSIONS
  Preterm birth and LBW were associated with an increased risk of current asthma into middle-age. These findings are the first to demonstrate the continuing impact of these characteristics on asthma risk into middle-age.
authors: a Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics , The University of Melbourne , Australia.
authors: Melanie C
authors: MC
authors: Matheson
authors: a Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics , The University of Melbourne , Australia.
authors: Ana López-Polín
authors: AL
authors: D Olhaberriague
authors: a Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics , The University of Melbourne , Australia.
authors: John A
authors: JA
authors: Burgess
authors: b Cancer Epidemiology Centre, Cancer Council Victoria.
authors: Graham G
authors: GG
authors: Giles
authors: a Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics , The University of Melbourne , Australia.
authors: John L
authors: JL
authors: Hopper
authors: c Menzies Research Institute, University of Tasmania , Australia.
authors: David P
authors: DP
authors: Johns
authors: d Department of Epidemiology & Preventive Medicine , Monash University , Melbourne , Australia.
authors: Michael J
authors: MJ
authors: Abramson
authors: c Menzies Research Institute, University of Tasmania , Australia.
authors: E Haydn
authors: EH
authors: Walters
authors: a Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics , The University of Melbourne , Australia.
authors: Shyamali C
authors: SC
authors: Dharmage
mesh_terms: D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000453:epidemiology*; D001315:Australia / Q000453:epidemiology; D002648:Child; D005260:Female; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D008297:Male; D047928:Premature Birth / Q000453:epidemiology*; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology; D012959:Socioeconomic Factors; D055815:Young Adult
keywords: Asthma; low birth weight; prematurity; small for gestational age