SAN DIEGO – The use of oral antibiotics before 4 years of age was associated with a significantly increased risk of later overweight in a large cohort study.
“Antibiotics may provide a physician-modifiable risk factor for obesity prevention in early childhood,” Dr. Elizabeth Dawson-Hahn said at the annual meeting of the Pediatric Academic Societies.
Dr. Elizabeth Dawson-Hahn
The study included 4,938 children born at Group Health Cooperative, the Seattle-based integrated health care system. Their electronic medical records indicated that 3,533 of them, or 72%, filled one or more prescriptions for oral antibiotics at ages 0-47 months. In this group, 53% were less than 12 months old at the time of their first oral antibiotic exposure, while the rest were 12-47 months old.
At ages 48-59 months, roughly 12% of all study participants were overweight, as defined by a body mass index at or above the 85th percentile. The prevalence was similar regardless of whether a child was exposed to early oral antibiotics. However, the groups with and without early antibiotic exposure differed in key ways, including a more than threefold higher prevalence of childhood asthma in those with early antibiotic exposure.
In a prespecified logistic regression analysis adjusted for sex, Medicaid status, childhood asthma, race, maternal antibiotic exposure during pregnancy, delivery type, and birth weight, each course of oral antibiotics a child received up to 47 months of age was associated with a 3% increased likelihood of being overweight at 48-59 months – and children who got early oral antibiotics received a mean of 3.7 courses by age 47 months. Thus, early antibiotic exposure was associated on average with a significant 11% increased risk of later overweight (P = .005), reported Dr. Dawson-Hahn, a general pediatrics fellow at the University of Washington, Seattle.
The increased risk of overweight related to early antibiotics was concentrated in the children who received the medications in infancy. In another logistic regression analysis, children who got oral antibiotics prior to age 12 months were at an adjusted 20% increased risk of being overweight at ages 48-59 months, compared with children who didn’t receive oral antibiotics before 48 months of age. In contrast, the risk of overweight in kids who received oral antibiotics at ages 12-47 months wasn’t significantly different from the risk in the unexposed group.
Future studies should explore the mechanism of the observed relationship between early antibiotic exposure and later overweight, Dr. Dawson-Hahn said. One leading hypothesis is that the early exposure alters the composition of the developing gut microbiome. Antibiotics have been used for decades as a means of boosting the weight of livestock, she noted.
Dr. Dawson-Hahn said she is planning to reanalyze the data set to see if weight gain differed depending upon the type of antibiotic involved in an early exposure. More than 80% of children with early antibiotic exposure received amoxicillin.
One audience member noted that just because the health plan’s electronic pharmacy records show a prescription for oral antibiotics was filled doesn’t mean the child took the full course. Dr. Dawson-Hahn agreed, but noted that her study findings are consistent with the results of prior studies by other investigators in the past 2 years, which typically relied upon parental recall of antibiotic exposure.
“We thought documented prescription fill would be an improvement over that,” she added.
Dr. Dawson-Hahn’s study was funded by a Hearst Foundation Fellowship Award and a Ruth L. Kirschstein National Research Service Award. She reported having no relevant financial conflicts.