title: Preterm birth and inhaled corticosteroid use in 6- to 19-year-olds: a Swedish national cohort study.
abstract: OBJECTIVE
  Preterm birth is associated with respiratory morbidity later in life, including asthma. Previous studies have mainly focused on asthma in early childhood in children born extremely preterm. In this study, we examined the risk of asthma in a national cohort of schoolchildren grouped according to degree of immaturity expressed as completed gestational weeks at birth.
  
  
  METHODS
  This was a register study in a Swedish national cohort of 1 100 826 children 6 to 19 years old. Retrieval of at least 1 prescription of inhaled corticosteroids (ICS) during 2006 was used as the main indicator for asthma. Logistic regression was used to test hypotheses, with adjustment for multiple socioeconomic and perinatal indicators.
  
  
  RESULTS
  Degree of immaturity, expressed as completed gestational weeks at birth, had an inverse dose-response relationship with ICS use. Compared with children born between 39 and 41 weeks' gestation, the odds ratio for ICS use increased with the degree of prematurity, from 1.10 (95% confidence interval: 1.08-1.13) for children born in weeks 37 to 38, to 2.28 (95% confidence interval: 1.96-2.64) for children born in weeks 23 to 28, after adjustment for confounders. The increase in ICS use with decreasing gestational age at delivery was similar in boys and girls, and declined with older age.
  
  
  CONCLUSIONS
  Preterm birth increased the risk of ICS use in these 6- to 19-year-olds by degree of immaturity, from extremely preterm to early term birth.
authors.affiliation: Division of Pediatrics, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden. hartmut.vogt@liu.se
authors.forename: Hartmut
authors.initials: H
authors.lastname: Vogt
authors.forename: Karolina
authors.initials: K
authors.lastname: Lindström
authors.forename: Lennart
authors.initials: L
authors.lastname: Bråbäck
authors.forename: Anders
authors.initials: A
authors.lastname: Hjern
mesh_terms: D000280:Administration, Inhalation; D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000008:administration & dosage*; D001249:Asthma / Q000188:drug therapy / Q000453:epidemiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000453:epidemiology*; D008297:Male; D011159:Population Surveillance; D011247:Pregnancy; D047928:Premature Birth; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000305:Adrenal Cortex Hormones