A new series of studies to be presented at the American Academy of Allergy, Asthma & Immunology’s Annual Meeting in Houston, Texas, states that an infant’s immune system development and susceptibility to asthma and allergies may be influenced not only by breastfeeding, but also gestational age at birth and whether or not the infant was delivered by Cesarean section.
The study finds that babies who were breastfed at 1 and 6 months had specific gut microbiome compositions, which the researchers say may affect immune system development for the better. Dr. Christine Cole Johnson, chair of the Department of Public Health Sciences at Henry Ford Hospital in Detroit, Michigan, says the findings further support the “hygiene hypothesis” — the idea that early childhood exposure to pathogens affects later-life risk of disease.
“For years now, we’ve always thought that a sterile environment was not good for babies. Our research shows why. Exposure to these micro-organisms, or bacteria, in the first few months after birth actually help stimulate the immune system. The immune system is designed to be exposed to bacteria on a grand scale. If you minimize those exposures, the immune system won’t develop optimally.”
In the studies, Dr. Johnson and colleagues set out to determine whether maternal or birth factors, as well as breastfeeding, affect the composition of gut bacteria — or the gut microbiome — in infants, and whether these compositions influence their risk of developing allergies or asthma. To reach their findings, the researchers analyzed data from the Wayne County Health, Environment, Allergy and Asthma Longitudinal Study (WHEALS), which investigates how environmental and biological factors influence the development of allergies and asthma in early life.
The researchers analyzed stool samples collected from babies at 1 and 6 months following birth.
The results of their analysis of stool samples collected from babies at 1 and 6 months following birth revealed that a mother’s race/ethnicity, an infant’s gestational age at birth, prenatal and postnatal tobacco smoke exposure, the presence of pets in the home, and whether a baby was born via Cesarean section or vaginal delivery influenced an infant’s gut microbiome composition.
Additionally, the researchers found that babies who were breastfed at 1 month were at lower risk of pet-related allergies.
Dr. Johnson gave her interpretation of the overall set of studies.
“The research is telling us that exposure to a higher and more diverse burden of environmental bacteria and specific patterns of gut bacteria appear to boost the immune system’s protection against allergies and asthma.”
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