Antibiotic Use in Early Childhood Modestly Increases Risk for Subsequent Obesity

Child taking pills, antibiotics
Child taking pills, antibiotics
The use of antibiotics in children younger than 24 months was modestly associated with being overweight and obese at age 5 years.

The use of antibiotics in children age <24 months was modestly associated with being overweight and obese by age 5 years, according to findings from a large cohort study published in Pediatrics.

Several studies have examined the relationship between antibiotic use in early childhood and subsequent obesity, but results have been mixed. In this study, researchers examined the association of antibiotic use with weight outcomes in a cohort of 362, 550 children from 35 healthcare institutions participating in the National Patient-Centered Clinical Research Network. The association between any antibiotic use at age <24 months with body mass index (BMI) z-score and being overweight or obese by age 48 to 72 months was evaluated. Secondary assessments included antibiotic spectrum and age-period exposures.

At age 5 years, the mean BMI z-score was 0.40 (SD 1.19) and 28% of participants were overweight or obese. When evaluating children without a complex chronic condition at age 5 years, the mean BMI z-score was estimated to be higher by 0.04 (95% CI, 0.03-0.05) and higher odds of overweight or obesity (odds ratio [OR], 1.05; 95% CI, 1.03-1.07) and higher odds of becoming overweight or obese (OR, 1.05; 95% CI, 1.03-1.07) associated with obtaining any antibiotics vs no antibiotics at age <24 months.

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“Although these small associations may have population-level effects on obesity, the clinical significance for individual patients is negligible,” the researchers concluded. “This weight gain effect will likely not be an influential factor when health care providers discuss the risks and benefits of antibiotics with parents.”


Block JP, Bailey LC, Gillman MW, et al. Early antibiotic exposure and weight outcomes in young children. Pediatrics.  2018;142(6):e20180290.