PCORnet Study Finds Link between Early Exposure to Antibiotics and Childhood Obesity

In the largest study to explore the connection between early exposure to antibiotics and childhood obesity, researchers with the Patient-Centered Clinical Research Network (PCORnet) found a small but consistent association between the use of antibiotics in the child’s first two years of life and a slightly greater risk of overweight or obesity at age 5. 

However, the researchers pointed out that the association was small—about a 5 percent increased risk—and concluded that the clinical significance of the findings for individual patients likely would be negligible.

 “The associations the group found were small enough that they are not likely to factor into decisions that doctors and parents make about prescribing antibiotics to young children,” said David M. Janicke, Ph.D., ABPP, a professor in UF’s Department of Clinical and Health Psychology. Janicke served as the OneFlorida site principal investigator for the PCORnet Antibiotics and Childhood Growth Study Group, which conducted the study. Results appeared in the December 2018 issue of Pediatrics

For example, the results showed that 5-year-old boys and girls of average height who were exposed to four or more courses of antibiotics before age 2 weighed about one-quarter pound more than 5-year-old children who did not receive antibiotics before age 2.

Antibiotics can affect the balance of naturally-occurring bacteria in the human digestive tract and intestines. These bacteria, known collectively as the gut microbiome, help with food digestion, metabolism, immunity and a host of other bodily functions.

Because the gut microbiome is established in early childhood and shows some stability after the first six months of life, there’s a concern that abrupt changes from antibiotics during early childhood could have long-term effects—including a propensity to gain excess weight.

Several other studies have examined the relationship between antibiotic use in infants and child obesity, but so far, the results have been mixed.

The PCORnet researchers examined electronic health record data of more than 362,000 children contributed by 35 affiliated institutions, including the OneFlorida Clinical Research Consortium. The scientists analyzed the relationship between antibiotics given to children ages 2 and younger and the children’s body weight once they reached age 5. About 60 percent had received at least one antibiotic prescription before age 2.

The association was strongest for children who had received four or more antibiotic courses.  Broad-spectrum antibiotic exposures were more consistently associated with higher BMI z-score and risk for overweight and obesity than narrow-spectrum antibiotics.

Results were similar regardless of whether or not a child had a chronic condition.

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