Childhood obesity risk: What role for antibiotics?

Babies who receive repeated doses of certain antibiotics between birth and 23 months of age have a higher risk of developing obesity in early childhood than babies who don’t, a 12-year study reveals.

The retrospective cohort study analyzed electronic health records from 2001 to 2013 for 64,580 children in a network of primary care practices affiliated with the Children’s Hospital of Philadelphia. It enrolled all children who had annual visits from birth to 23 months of age and at least 1 visit between 24 and 59 months. Researchers identified instances of antibiotic treatment to age 23 months, then assessed the children for obesity from 24 to 59 months using the National Health and Nutrition Examination Survey 2000 body mass index norms.

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Sixty-nine percent of the children in the study received antibiotics before age 24 months with a mean of 2.3 exposures per child. Children given antibiotics 4 or more times before age 24 months had an 11% greater risk of obesity between 24 and 59 months than children given no antibiotics, even after other risk factors were considered.

However, not all antibiotics had an equal effect. Cumulative exposure to broad-spectrum antibiotics-at least 4 times before age 24 months-was associated with a 16% higher risk of obesity between 24 and 59 months. The association didn’t hold for narrow-spectrum drugs at any age or frequency of exposure. The researchers considered narrow-spectrum antibiotics to be drugs used for first-line treatment of common pediatric infections-penicillin and amoxicillin, for example. Broad-spectrum antibiotics were defined as drugs that current guidelines recommend as second-line therapy.

Because the study found that common infections were often treated with broad-spectrum antibiotics, the researchers suggest that prescribing narrow-spectrum drugs may be 1 way to modify the risk of developing obesity. Previous research has shown that antibiotics influence the diversity and composition of intestinal microbes and may affect metabolism.

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