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References
Ainonen S, et al. Timing of early antibiotic exposure and the risk of overweight and obesity in children.
Presented at: Pediatric Academic Societies Meeting; April 24-28, 2025; Honolulu.
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.
Data derived from Ainonen S, et al. Timing of early antibiotic exposure and the risk of overweight and obesity in children. Presented at: Pediatric Academic Societies Meeting; April 24-28, 2025; Honolulu.
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.”
Early childhood antibiotic use raises risk for asthma, food allergy, allergic rhinitis
Healio Minute, April 30, 2025
Frequent use of antibiotics in infants and young children may increase risk for asthma, allergies and other conditions. https://www.rutgers.edu/news/frequent-use-antibiotics-infants-and-young-children-may-increase-risk-asthma-allergies-and. Published April 16, 2025. Accessed April 18, 2025.
The risk for food allergy, asthma and allergic rhinitis was elevated among children who received antibiotics in early childhood, and risk was greater with five-plus courses, according to data published in The Journal of Infectious Diseases.
“While antibiotics are assuredly useful and important drugs, this study underscores potential long-term risks to antibiotic treatment,” Daniel B. Horton, MD, MSCE, associate professor of pediatrics and epidemiology at Rutgers Robert Wood Johnson Medical School and Rutgers School of Public Health, told Healio.
Data were derived from Beier MA, et al. J Infect Dis. 2025;doi:10.1093/infdis/jiaf191.
“Particularly for infants and young children whose infections may not warrant antibiotics, these potential long-term risks need to be weighed against the potential risks of watchful waiting and supportive care,” Horton, who also is a member of the Center for Pharmacoepidemiology and Treatment Science within Rutgers Institute for Health, Health Care Policy and Aging Research, said.
In this retrospective cohort study, Horton and colleagues assessed 1,091,449 children from U.K. electronic health records spanning from 1987 to 2020 to determine if early-childhood (between birth and 2 years) antibiotic exposure is linked to diagnosis of different types of conditions: asthma/allergic, autoimmune and neurodevelopmental/psychiatric.
Within the population, more children had vs. did not have early-childhood antibiotic exposure (685,665 children vs. 405,784 children).
In a model that accounted for maternal, child and area-based socioeconomic covariates, researchers found a heightened risk for four conditions with early-childhood antibiotic exposure. These included food allergy (adjusted HR = 1.33; 95% CI, 1.26-1.4), asthma (aHR = 1.24; 95% CI, 1.22-1.26), allergic rhinitis (aHR = 1.06; 95% CI, 1.03-1.1) and atopic dermatitis (aHR = 1.07; 95% CI, 1.05-1.08).
Notably, those with five or more antibiotic courses faced a greater risk for three of the above conditions vs. those with one to two courses, according to the study: food allergy (aHR = 1.53; 95% CI, 1.42-1.64), asthma (aHR = 1.52; 95% CI, 1.49-1.55) and allergic rhinitis (aHR = 1.18; 95% CI, 1.13-1.23).
Researchers also investigated links, both without and with dose-response, in sibling-matched analyses and reported comparable findings.
Compared with one to two antibiotic courses, those with five or more courses in early childhood had an increased risk for intellectual disability in both the adjusted analysis (aHR = 1.73; 95% CI, 1.49-2.01) and sibling-matched analysis (aHR = 2.79; 95% CI, 1.87-4.18), according to the study.
“I was surprised by the strength of association between repeated antibiotic exposures and intellectual disability — much stronger than a previous study that looked at learning disorders more broadly,” Horton told Healio. “While the findings are concerning at first blush, the limitations and alternative explanations make me want to see these findings substantiated elsewhere using different methods.”
In contrast, researchers did not observe a significant relationship between early-childhood antibiotic exposure and celiac disease, inflammatory bowel disease, juvenile idiopathic arthritis, psoriasis, type 1 diabetes, autism spectrum disorders or anxiety when analyzing the full cohort.
Sibling-matched analysis was also not significant for attention-deficit/hyperactivity disorder, which previously had a weak link to early antibiotic exposure in the full-cohort (aHR = 1.08; 95% CI, 1.02-1.15), according to the study.
Based on sibling-matched analysis results of a negative control outcome (forearm fracture), the study reported minimal confounding bias.
“It would be ideal to look not just at patterns of antibiotic exposure in relation to the development of chronic pediatric conditions, but also at the microbiome directly, to see whether disruption of the microbiome actually explains these relationships,” Horton told Healio. “Large prospective cohorts can be particularly helpful for this.”
