title: Association of antibiotics in infancy with early childhood obesity.
abstract: OBJECTIVE
  Obesity in children and adults is associated with significant health burdens, making prevention a public health imperative. Infancy may be a critical period when environmental factors exert a lasting effect on the risk for obesity; identifying modifiable factors may help to reduce this risk.
  
  
  OBJECTIVE
  To assess the impact of antibiotics prescribed in infancy (ages 0-23 months) on obesity in early childhood (ages 24-59 months).
  
  
  METHODS
  We conducted a cohort study spanning 2001-2013 using electronic health records. Cox proportional hazard models were used to adjust for demographic, practice, and clinical covariates. The study spanned a network of primary care practices affiliated with the Children's Hospital of Philadelphia including both teaching clinics and private practices in urban Philadelphia, Pennsylvania, and the surrounding region. All children with annual visits at ages 0 to 23 months, as well 1 or more visits at ages 24 to 59 months, were enrolled. The cohort comprised 64,580 children.
  
  
  METHODS
  Treatment episodes for prescribed antibiotics were ascertained up to 23 months of age.
  
  
  METHODS
  Obesity outcomes were determined directly from anthropometric measurements using National Health and Nutrition Examination Survey 2000 body mass index norms.
  
  
  RESULTS
  Sixty-nine percent of children were exposed to antibiotics before age 24 months, with a mean (SD) of 2.3 (1.5) episodes per child. Cumulative exposure to antibiotics was associated with later obesity (rate ratio [RR], 1.11; 95% CI, 1.02-1.21 for ≥ 4 episodes); this effect was stronger for broad-spectrum antibiotics (RR, 1.16; 95% CI, 1.06-1.29). Early exposure to broad-spectrum antibiotics was also associated with obesity (RR, 1.11; 95% CI, 1.03-1.19 at 0-5 months of age and RR, 1.09; 95% CI, 1.04-1.14 at 6-11 months of age) but narrow-spectrum drugs were not at any age or frequency. Steroid use, male sex, urban practice, public insurance, Hispanic ethnicity, and diagnosed asthma or wheezing were also predictors of obesity; common infectious diagnoses and antireflux medications were not.
  
  
  CONCLUSIONS
  Repeated exposure to broad-spectrum antibiotics at ages 0 to 23 months is associated with early childhood obesity. Because common childhood infections were the most frequent diagnoses co-occurring with broad-spectrum antibiotic prescription, narrowing antibiotic selection is potentially a modifiable risk factor for childhood obesity.
authors.affiliation: Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania2Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia.
authors.forename: L Charles
authors.initials: LC
authors.lastname: Bailey
authors.affiliation: Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania2Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia.
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Forrest
authors.affiliation: Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: Peixin
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania3Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Richards
authors.affiliation: Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: Alice
authors.initials: A
authors.lastname: Livshits
authors.affiliation: Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania2Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia.
authors.forename: Patricia A
authors.initials: PA
authors.lastname: DeRusso
mesh_terms: D000900:Anti-Bacterial Agents / Q000009:adverse effects*; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D063766:Pediatric Obesity / Q000139:chemically induced*; D016016:Proportional Hazards Models; D012307:Risk Factors
chemical_list: D000900:Anti-Bacterial Agents