UCSF

We investigated the relationship between early antibiotic exposure before 6 months age and risk for obesity at 2 years in a high-risk, low-income, urban Latino cohort (n = 97), with the hypothesis that antibiotic exposure would increase risk for obesity by 2 years. Data were collected through maternal report of infant 24-hour dietary intake at 4-6 weeks, 6 months, 1, and 2 years; and food frequency questionnaires at 4-6 weeks, 6 months, 1, and 2 years. Antibiotic use data, including type and frequency, were collected through maternal self-report at 6 months and 1 year. Cord blood levels of leptin and insulin were measured at birth. Chi-squared tests were used to assess the relationship between obesity and dichotomous predictors and Student's t-tests for continuous predictors. Multivariable logistic models were used to ascertain independent predictors of obesity at age 2. We found that early antibiotic exposure before 6 months was independently associated with increased risk for rapid infant weight gain [odds ratio (OR) 6.42, 95% confidence interval (CI, defined as the range in which sample will fall with 95% confidence: 1.17-35.06)] and obesity at age 2 [OR 6.15, 95% CI (1.03-36.70)]. These findings provide evidence promoting antibiotic stewardship in pediatric practices to minimize exposure in the first 6 months of life.