Antibiotic Prescriptions and the Risk of Overweight or Obesity in Children aged 2-17 years: A French Retrospective Primary Care Cohort Study

Background/Objectives : Several factors have been associated with the increase in the prevalence of childhood overweight and obesity, including exposure to antibiotics. While recent studies suggest a potential link, few data exist for children older than two years old, and none have been conducted in the French population. The objective is to investigate the association between antibiotic prescriptions and the onset of overweight or obesity among children aged 2–17 years. Subjects/Methods : A retrospective cohort study was conducted using data from the French primary care database PRIMEGE (2012–2022). Children aged 2–17 with an initial BMI classified as normal were included ia 8 353 children (47 054 person-years). Antibiotic exposure was assessed both as the average annual number of prescriptions received along childhood and as the absolute number of prescriptions between 2 and 4 years old. The main outcome was the onset of overweight or obesity (IOTF criteria). Estimation of dose response relationship was estimated with Relative Risks (RRs) using quasi-Poisson regression models, adjusted for sex, age, and medical centres. Results : Among included children, 1 026 developed overweight or obesity. A significant dose–response relationship was identified in the trend analysis between the annual mean number of antibiotic prescriptions and the onset of overweight or obesity (RR = 1.20; 95% CI: 1.11–1.29; p < 0.001), indicating a 20% higher risk for each additional antibiotic prescription per year. Similarly, when considering the absolute number of antibiotic prescriptions between ages 2 and 4, a significant association was also observed (RR = 1.09; 95% CI: 1.03–1.14; p < 0.001). Conclusion: These findings strengthen concerns that antibiotic exposure may contribute to overweight and obesity during childhood. They support the need for further evaluation of modifiable risk factors for excess weight.