Use of Broad-Spectrum Antibiotics Before Age 2 Associated with Obesity Risk


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JAMA Pediatrics

Bottom Line: The use of broad-spectrum antibiotics by children before the age of 24 months was associated with increased risk of obesity in early childhood.

Author: L. Charles Bailey, M.D., Ph.D., of the Children’s Hospital of Philadelphia, and colleagues.

Background: Obesity is a major public health problem. Previous research suggests intestinal microflora may be associated with obesity, and antibiotic exposure may affect microbial diversity and composition.

How the Study Was Conducted: The authors used electronic health records spanning from 2001 to 2013 from a network of primary care clinics. All children with annual visits at ages 0 to 23 months, as well as one or more visit at ages 24 to 59 months were enrolled. The final group included 64,580 children. Children were followed-up until they were 5 years old.

Results: The study found 69 percent of the children were exposed to antibiotics before the age of 24 months with an average exposure of 2.3 episodes per child. An increased risk of obesity was associated with greater antibiotic use, especially for children with four or more exposures, when all antibiotics or only broad-spectrum antibiotics were examined. No association was seen between obesity and narrow-spectrum antibiotics. For all children, the prevalence of obesity was 10 percent at age 2 years, 14 percent at 3 years and 15 percent at 4 years. The prevalence of being overweight/obese was 23 percent, 30 percent and 33 percent, respectively.

Discussion: “Because obesity is a multifactorial condition, reducing prevalence depends on identifying and managing multiple risk factors whose individual effects may be small but modifiable. Our results suggest that the use of broad-spectrum outpatient antibiotics before age 24 months may be one such factor. This provides additional support for the adoption of treatment guidelines for common pediatric conditions that emphasize limiting antibiotic use to cases where efficacy is well demonstrated and preferring narrow-spectrum drugs in the absence of specific indications for broader coverage.”

(JAMA Pediatr. Published online September 29, 2014. doi:10.1001/jamapediatrics.2014.1539. Available pre-embargo to the media at

Editor’s Note: Funding was provided by an unrestricted donation from the American Beverage Foundation for a Healthy America to the Children’s Hospital of Philadelphia to support the Healthy Weight Program. Please see article for additional information, including other authors, author contributions and affiliations, etc.

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