title: Gestational Age, Birthweight for Gestational Age, and Childhood Hospitalisations for Asthma and Other Wheezing Disorders.
abstract: BACKGROUND
  Preterm birth, early term birth, and low birthweight are associated with childhood wheezing disorders in developed Western settings, but observed associations could be confounded by socio-economic position. This study aims to clarify such associations in a developed non-Western setting with a different confounding structure.
  
  
  METHODS
  Using Cox regression, we examined the adjusted associations of gestational age and birthweight for gestational age with time to first public hospital admission for asthma, bronchitis, and bronchiolitis (International Classification of Diseases, Ninth Version Clinical Modification 466, 490, and 493) from 9 days to 12 years in a population-representative birth cohort of 8327 Chinese children in Hong Kong, a developed setting with less clear social patterning of prematurity or birthweight. Analyses were adjusted for infant and parental characteristics and socio-economic position.
  
  
  RESULTS
  Children born late preterm (34 to <37 weeks) had higher risk of hospitalisation for asthma and other wheezing disorders [hazard ratio (HR) 1.99, 95% confidence interval (CI) 1.48, 2.67] than children born full term (39 to <41 weeks). Early term births (37 to <39 weeks) had HR 1.01 (95% CI 0.84, 1.22), late term births (41 to <42 weeks) had HR 0.77 (95% 0.59, 1.01), and post-term births (≥42 weeks) had HR 0.56 (95% CI 0.32, 0.98). Large for gestational age was associated with lower risk of hospitalisation (HR 0.76, 95% CI 0.57, 0.99).
  
  
  CONCLUSIONS
  The association of preterm birth with childhood wheezing could be biologically mediated. We cannot rule out an association for early term births.
authors.affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: June Y Y
authors.initials: JY
authors.lastname: Leung
authors.affiliation: Department of Paediatrics, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Hugh S
authors.identifier: http://orcid.org/0000-0001-9912-0544
authors.initials: HS
authors.lastname: Lam
authors.affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: Gabriel M
authors.initials: GM
authors.lastname: Leung
authors.affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.|School of Public Health and Hunter College, City University of New York, New York.
authors.forename: C Mary
authors.initials: CM
authors.lastname: Schooling
mesh_terms: D001249:Asthma / Q000503:physiopathology / Q000628:therapy*; D001724:Birth Weight / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005865:Gestational Age; D006723:Hong Kong; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D047928:Premature Birth / Q000503:physiopathology; D012135:Respiratory Sounds / Q000503:physiopathology*
keywords: asthma; birthweight; children; cohort study; gestational age; wheeze