title: Use of antibiotics during pregnancy increases the risk of asthma in early childhood.
abstract: OBJECTIVE
  To investigate the hypothesis that mother's use of antibiotics in pregnancy could influence asthma and eczema in early life.
  
  
  METHODS
  Subjects were included from the Copenhagen Prospective Study on Asthma in Childhood cohort of children born of mothers with asthma (N = 411). Severe asthma exacerbations and eczema were diagnosed by research unit physicians. Replication was sought in children from the Danish National Birth Cohort (N = 30 675). Asthma outcomes were hospitalization and use of inhaled corticosteroids. Eczema was defined by an algorithm developed from cases of clinically verified eczema. All children were followed to age 5 years in a cohort study design.
  
  
  RESULTS
  The Copenhagen Prospective Study on Asthma in Childhood data showed increased risk of asthma exacerbation (hazard ratio 1.98 [95% CI 1.08-3.63]) if mothers had used antibiotics during third trimester. The Danish National Birth Cohort confirmed increased risk of asthma hospitalization (hazard ratio 1.17 [1.00-1.36]), and inhaled corticosteroids (1.18 [1.10-1.27]) in the children if mothers used antibiotics any time during pregnancy. In the subgroup of mothers using antibiotics for nonrespiratory infection, the children also had increased risk of asthma.
  
  
  CONCLUSIONS
  We found increased risk of asthma associated with maternal antibiotic use in a clinical study of a birth cohort with increased risk of asthma and replicated this finding in an unselected national birth cohort, and in a subgroup using antibiotics for nonrespiratory infections. This supports a role for bacterial ecology in pre- or perinatal life for the development of asthma.
authors.affiliation: Copenhagen Prospective Studies on Asthma in Childhood, Faculty of Health Sciences, University of Copenhagen, and The Danish Pediatric Asthma Center, Copenhagen University Hospital, Gentofte, Copenhagen, Denmark. LGN@ssi.dk
authors.forename: Lone Graff
authors.initials: LG
authors.lastname: Stensballe
authors.forename: Jacob
authors.initials: J
authors.lastname: Simonsen
authors.forename: Signe M
authors.initials: SM
authors.lastname: Jensen
authors.forename: Klaus
authors.initials: K
authors.lastname: Bønnelykke
authors.forename: Hans
authors.initials: H
authors.lastname: Bisgaard
mesh_terms: D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000465:Algorithms; D000900:Anti-Bacterial Agents / Q000009:adverse effects*; D001249:Asthma / Q000209:etiology*; D002675:Child, Preschool; D015331:Cohort Studies; D003718:Denmark; D004485:Eczema / Q000209:etiology; D005260:Female; D006760:Hospitalization; D006801:Humans; D008297:Male; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000188:drug therapy; D011297:Prenatal Exposure Delayed Effects; D012306:Risk; D016896:Treatment Outcome
chemical_list: D000305:Adrenal Cortex Hormones; D000900:Anti-Bacterial Agents