ANTIBIOTICS IN INFANCY AND CHILD DEVELOPMENT: WHAT RESEARCH SHOWS
When a baby gets sick, antibiotics can be lifesaving. But new research is raising important questions about what happens when these powerful medicines are used too much or too early in life. Scientists are discovering that excessive antibiotic use during infancy may have unexpected effects on how children develop, particularly in their gut health and long-term wellness.
THE CRITICAL WINDOW: EARLY LIFE AND THE MICROBIOME
The first year of a child’s life is a crucial time. During this period, trillions of bacteria colonize the infant’s digestive system, creating what scientists call the microbiome. This microbial community is not just about digestion. It plays a fundamental role in immune system development, how the body processes nutrients, and even how various organs function. When antibiotics are introduced during this sensitive window, they can disrupt the natural development of this bacterial community in ways that may have lasting consequences.
Research published in recent studies shows that children treated with antibiotics in early life experience significant changes in their gut bacteria. Specifically, they lose important beneficial bacteria like Faecalibacterium prausnitzii, Clostridium leptum, Bacteroides species, and certain Bifidobacteria strains. These are not random bacteria. They perform specific functions that support healthy development and immune function. When they disappear, the balance of the microbiome shifts in unhealthy ways, a condition called dysbiosis.
ANTIBIOTICS AND MICROBIOME DISRUPTION
The disruption caused by antibiotics is particularly severe in newborns and premature infants. Their microbiomes are still forming, and they are especially vulnerable to imbalances. When antibiotics kill off beneficial bacteria along with harmful ones, resistant bacterial strains can take over. This creates a pro-inflammatory environment in the gut, meaning the intestines become inflamed and irritated. Over time, this inflammation can have effects that extend far beyond the digestive system.
One concerning finding involves bacteria carrying genes called colibactin genes. Infants in neonatal intensive care units who received antibiotics in their first 30 days of life showed higher levels of these bacteria compared to full-term infants who did not receive early antibiotics. Some of these colibactin-carrying bacteria, particularly Klebsiella pneumoniae, may play a role in disease development later in life. The research suggests that antibiotic use in early life influences which microbes colonize the infant gut, potentially setting the stage for health problems years later.
THE NEUROLOGICAL CONNECTION
Perhaps most intriguingly, researchers are investigating links between early antibiotic use and neurological development. Some studies suggest that reducing or altering antibiotic-resistant strains through excessive antibiotic use may contribute to the development of chronic diseases and neurological disorders, including autism spectrum disorder. While this connection is still being studied and is not yet fully understood, it highlights why scientists are concerned about casual or unnecessary antibiotic use in infants.
EFFECTS ON LUNG DEVELOPMENT
Beyond the gut, antibiotics given to mothers during specific periods of nursing can affect their infants’ lung development. Research shows that when mothers receive antibiotics between 10 and 20 days after birth, their nursing infants experience changes in lung function. These infants develop smaller air sacs in their lungs and show increased airway reactivity, meaning their airways become more sensitive and prone to constriction. This altered lung development is associated with increased risk of asthma and other chronic lung diseases later in life. The mechanism appears to involve an exaggerated recruitment of immune cells called eosinophils to the developing lungs, disrupting normal lung growth patterns.
THE BIGGER PICTURE: WHEN ANTIBIOTICS ARE NECESSARY
It is important to understand that antibiotics save lives. Newborns and infants can develop serious infections that require immediate antibiotic treatment. The concern is not about using antibiotics when they are truly needed, but about overuse and unnecessary use. Many infants receive antibiotics without clear evidence of bacterial infection, or they receive them for longer than necessary.
Recent research demonstrates that using better diagnostic tools can reduce unnecessary antibiotic exposure. For example, using C-reactive protein testing to guide antibiotic decisions reduced treatment duration in neonates with signs of infection from 6.6 days to 5.1 days, and in children aged 6 months to 12 years from 6.7 days to 4.8 days. These reductions in antibiotic exposure happened without compromising safety, suggesting that many infants are currently receiving antibiotics longer than needed.
RESTORING BALANCE AFTER ANTIBIOTIC USE
Scientists are actively researching ways to protect and restore the microbiome after antibiotic treatment. Probiotics and prebiotics show promise in reducing the risk of dysbiosis and helping restore bacterial balance in the gut. These approaches may become standard practice alongside antibiotic therapy to minimize long-term damage to developing microbiomes.
The evidence suggests that while antibiotics are essential tools in pediatric medicine, their use in infancy should be carefully considered and monitored. Excessive or unnecessary antibiotic use during this critical developmental window may have consequences that extend into childhood and beyond, affecting immune function, lung development, and potentially neurological development. Healthcare providers are increasingly recognizing the need to balance the life-saving benefits of antibiotics against the risks of microbiome disruption during this vulnerable period of human development.
SOURCES
https://pmc.ncbi.nlm.nih.gov/articles/PMC12729859/
https://www.tandfonline.com/doi/full/10.1080/19490976.2025.2604874
https://pmc.ncbi.nlm.nih.gov/articles/PMC12725598/
https://www.frontiersin.org/journals/immunology/articles/10.3389
