Differences in mothers’ and infants’ gut bacteria may influence early infections.
A recent study in Finland suggests that tiny differences in gut bacteria in mothers and their newborns may influence whether infants develop respiratory infections in their first months. Researchers followed over a thousand full-term infants and their mothers, tracking infections during the babies’ first six months. They also analyzed stool samples from mothers near delivery and from infants at three and six weeks to see how microbial communities might relate to illness.
About 18 percent of infants in the study developed respiratory infections serious enough to require a doctor visit, including fevers and ear infections. Most infections were upper respiratory, though a small number affected the lower respiratory tract. About 30 percent of infections happened in the first three months of life, highlighting a period of heightened vulnerability. Families kept detailed logs of symptoms and medical visits, providing precise information on the timing and severity of infections.
The researchers found that mothers of infants who later became sick carried higher amounts of certain bacteria, including Enterococcus, Citrobacter, and Enterobacter, while Clostridium was less common. These bacteria can act as opportunistic pathogens, suggesting that small imbalances in maternal gut microbes could influence infant health. For infants, the overall microbial diversity at three and six weeks was similar across groups, but those who developed infections had higher levels of specific bacterial families and genera, such as Rikenellaceae, Prevotellaceae, Verrucomicrobiaceae, Alistipes, Akkermansia, Faecalibacterium, Peptoniphilus, and Serratia.
Some of these findings challenge previous assumptions. Faecalibacterium, for example, has often been linked to respiratory protection, but in this study, higher levels appeared in infants who developed infections. By six weeks, infants prone to infections showed lower levels of Anaerostipes, another bacterium that produces butyrate, a substance important for gut and immune health. Researchers suggested that the early presence of certain adult-type butyrate-producing bacteria might indicate premature gut maturation, which could make infants more vulnerable to respiratory infections.
The study took care to exclude infants who were already sick at the time of sampling and matched cases and controls based on factors like birth season, sex, and delivery mode. This strengthened the reliability of the associations between gut bacteria and infection risk. However, the authors note that these findings show correlations rather than direct cause-and-effect. The population studied was relatively uniform, with all infants healthy, full-term, and mostly breastfed, which may limit how broadly the results apply.
Despite these limits, the study offers new insights. It suggests that both maternal and early infant gut bacteria might play a role in shaping immune responses and vulnerability to infection. Researchers hope that future studies could explore whether adjusting gut bacteria—through diet, probiotics, or other interventions—might reduce the risk of respiratory illness in young infants. The work adds to a growing understanding that the gut microbiome is linked not only to long-term health outcomes like asthma and allergies but also to immediate infection risks in early life.
This Finnish research highlights the delicate balance of gut bacteria during a critical window for infant immunity. Subtle changes in microbial communities, in both mothers and babies, may signal increased susceptibility to infections. While much remains to be learned, these findings point to potential strategies for early prevention, suggesting that supporting a healthy gut microbiome could be one path toward protecting infants during their first months.
Sources:
Gut bacteria in mothers and newborns may shape infants’ risk of early respiratory infections
The association of maternal and infant early gut microbiota with respiratory infections in infants
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