A baby’s gut microbes may help rewrite part of the developmental story that begins before birth. Researchers in Hong Kong have found that epigenetic changes present at birth can influence how gut bacteria develop during the first year of life, and certain combinations of those microbes were linked to early signs of autism and ADHD by age three.
Epigenetic settings at birth shape the infant microbiome
The study, published in Cell Press Blue, was led by scientists at The Chinese University of Hong Kong. They analyzed DNA methylation patterns in umbilical cord blood from 571 infants. DNA methylation is a common form of epigenetic modification, a kind of biological switch that can turn genes on or off. The team then combined those data with gut microbiome samples collected from 969 infants at 2, 6, and 12 months of age. They also took microbiome samples from the infants’ parents during the third trimester of pregnancy. When the children reached 36 months old, researchers assessed their neurodevelopment using a behavioral questionnaire and looked for connections between developmental outcomes, gut microbes, and epigenetic patterns.
Certain bacteria appear to offer protection
Senior author Francis Ka Leung Chan, a gastroenterologist at The Chinese University of Hong Kong, said that certain bacteria seem to offer protection, which is exciting because it suggests there could be ways to support a child’s development through diet or probiotics in the future. Co-senior author Hein Min Tun, a public health researcher at the same university, described the finding as a kind of conversation happening: a baby’s epigenetic setting at birth can influence their risk for neurodevelopmental disorders, but the presence of certain good bacteria in their gut can step in and modify the risk.
Factors that influence the infant microbiome
The researchers found that several factors were associated with epigenetic patterns at birth, including delivery method, length of pregnancy, having older siblings, and maternal allergies. Interestingly, parental gut microbiomes did not appear to influence these birth-related epigenetic changes. The development of the infant microbiome was linked to a different set of factors: delivery method, antibiotic exposure, older siblings, and breastfeeding.
This study does not prove that gut bacteria cause or prevent autism and ADHD. It shows a correlation between epigenetic patterns, microbial composition, and later behavioral assessments. The significance lies in the timing: the first few years of life are a critical period for both brain development and the maturation of the immune system. Previous research had shown that epigenetics and the gut microbiome can each influence long-term health, but scientists had limited understanding of how these two systems interact during early life. This work opens a door to future research on whether modifying the infant microbiome through diet or probiotics could alter developmental trajectories.
