title: Prenatal exposure to systemic antibacterials and overweight and obesity in Danish schoolchildren: a prevalence study.
abstract: OBJECTIVE
  Prenatal exposure to antibacterials may permanently dysregulate fetal metabolic patterns via epigenetic pathways or by altering maternal microbiota. We examined the association of prenatal exposure to systemic antibacterials with overweight and obesity in schoolchildren.
  
  
  METHODS
  We conducted a prevalence study among Danish schoolchildren aged 7-16 years using data from routine school anthropometric evaluations conducted during 2002-2013. Prenatal exposure to antibacterials was ascertained by using maternal prescription dispensations and infection-related hospital admissions during pregnancy. We defined overweight and obesity among the children using standard age- and sex-specific cutoffs. We computed sex-specific adjusted prevalence ratios (aPRs) of overweight and obesity associated with exposure to prenatal antibacterials, adjusting for maternal age at delivery, marital status, smoking in pregnancy and multiple gestation; we also stratified the analyses by birth weight.
  
  
  RESULTS
  Among 9886 schoolchildren, 3280 (33%) had prenatal exposure to antibacterials. aPRs associated with the exposure were 1.26 (95% confidence interval (CI): 1.10-1.45) for overweight and 1.29 (95% CI: 1.03-1.62) for obesity. Among girls, aPRs were 1.16 (95% CI: 0.95-1.42) for overweight and 1.27 (95% CI: 0.89 to 1.82) for obesity. Among boys, aPRs were 1.37 (95% CI: 1.13-1.66) for overweight and 1.29 (95% CI: 0.96-1.73) for obesity. The aPR for overweight was higher among schoolchildren with birth weight <3500 g (aPR: 1.30, 95% CI: 1.05-1.61) than in schoolchildren with birth weight ⩾3500 g (aPR: 1.18, 95% CI: 0.95-1.46). Inversely, the association for obesity was higher among schoolchildren with birth weight ⩾3500 g (aPR: 1.35, 95% CI: 1.00-1.81) than among those who were <3500 g at birth (aPR: 1.16, 95% CI: 0.82-1.65).
  
  
  CONCLUSIONS
  Prenatal exposure to systemic antibacterials is associated with an increased risk of overweight and obesity at school age, and this association varies by birth weight.
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Mor
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: S
authors.initials: S
authors.lastname: Antonsen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: J
authors.initials: J
authors.lastname: Kahlert
authors.affiliation: Child and Adolescent Health Section, Department of Family and Employment, Municipality of Aalborg, Aalborg, Denmark.
authors.forename: V
authors.initials: V
authors.lastname: Holsteen
authors.affiliation: Child and Adolescent Health Section, Department of Family and Employment, Municipality of Aalborg, Aalborg, Denmark.
authors.forename: S
authors.initials: S
authors.lastname: Jørgensen
authors.affiliation: Child and Adolescent Health Section, Department of Family and Employment, Municipality of Aalborg, Aalborg, Denmark.
authors.forename: J
authors.initials: J
authors.lastname: Holm-Pedersen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: H T
authors.initials: HT
authors.lastname: Sørensen
authors.affiliation: Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Metabolic Genetics, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: O
authors.initials: O
authors.lastname: Pedersen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: V
authors.initials: V
authors.lastname: Ehrenstein
mesh_terms: D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000009:adverse effects; D015992:Body Mass Index; D002648:Child; D003718:Denmark / Q000453:epidemiology; D005260:Female; D047109:Fetal Development / Q000187:drug effects*; D006801:Humans; D008297:Male; D009035:Mothers; D063766:Pediatric Obesity / Q000139:chemically induced / Q000453:epidemiology*; D011247:Pregnancy; D037841:Pregnant People; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology*; D015995:Prevalence; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*
chemical_list: D000900:Anti-Bacterial Agents