Another study links early antibiotic therapy to elevated BMI in children

HONOLULU — The results of a large observational study provided more evidence that receiving antibiotics in the first 2 years of life can increase a child’s risk for obesity, researchers reported.

The study did not see a similar relationship between antibiotic use in the year leading up to a pregnancy all the way through the perinatal period, according to results presented at PAS by Sofia Ainonen, MD, a pediatric resident at the Oulu University Hospital in Oulu, Finland.

Although other studies have produced similar results, Ainonen and colleagues said some of the specifics regarding the association between antibiotics and elevated BMI in childhood remain poorly understood, including the importance of the timing of the exposure.

In their study, they assessed the timing of antibiotic exposure among more than 33,000 children delivered vaginally in Finland for any related association with BMI at age 2 years or overweight or obesity at age 12 years.

Most children in the study — 68% — received antibiotics in the first 2 years of life, according to Ainonen and colleagues. Exposure was also common among mothers in the year before their pregnancies, 39% of whom received antibiotics. The rate of antibiotic exposure was 27% among mothers during pregnancy and 21% among babies in the perinatal period.

The researchers used modeling to check for associations between antibiotic exposure and weight, adjusting for factors such as maternal age, gestational diabetes, smoking during pregnancy and many other maternal factors that could skew the results.

They found that children who received antibiotics had an adjusted BMI score that was 0.067 higher than unexposed children (95% CI, 0.041-0.094) at age 2 years, These children were 9% more likely to have overweight (adjusted HR = 1.09; 95% CI 1.04-1.14).

The association remained at age 12 years, by which time participants who had received antibiotics by age 2 years had a 20% greater risk for obesity (aHR = 1.2; 95% CI, 1,1-1.31).

The study did not assess specific antibiotics to determine if any groups were more likely to increase a child’s risk for obesity than others, Ainonen told Healio.

And because the study was observational, it is possible there are other factors that explain the results, she said. For example, “children from families in obesity-related environments may be more likely to receive antibiotics,” Ainonen said. But she also noted other reasons why children who receive antibiotics early in life might gain excess weight.

“The growth-promoting effects of antibiotics have been reported earlier in both animal studies and in observational studies in humans, and they are still not well understood,” Ainonen said.

“One potential mechanism could be alterations in the children’s gut microbiota composition. Individuals with obesity exhibit differences in gut microbiota composition compared to their lean counterparts,” she continued.

The take-home message for clinicians is not that young children should not be prescribed antibiotics, Ainonen said. Rather, like a lot of other research, the new study highlights the importance of stewardship and in being judicious in prescribing antibiotics to children.

The researchers advocated for public health interventions that address antibiotic prescribing in the first 2 years of life.

“Antibiotics are undoubtedly lifesaving intervention,” Ainonen said. “However, our finding highlights cautious antibiotic prescribing and avoiding unnecessary courses of antibiotics — for example, for upper respiratory tract infections in children,” Ainonen said. “It also highlights the importance of preventing childhood infections.”

For more information:

Sofia Ainonen, MD, can be reached at sofia.ainonen@oulu.fi.