i) Mother’s Microbiome- A study cited by Nuriel-Ohayon et al. demonstrated the ability of the mother to pass on bacteria to the child by giving a mouse a certain species of bacteria and examining the offspring’s GI tract, finding said bacteria present there. Obviously this makes sense due to the intimate nature of mother and child where they are interacting and touching, allowing for transference of microbes, the first that the baby is exposed to.
ii) Mode of delivery- Studies have shown that newborns delivered vaginally adopt the microbiome of the mother’s vagina early on, where as those delivered by C-section adopt that of the mother’s skin. The difference was present all the way to the oral microbiome of the baby, where the same results were found. The Nuriel-Ohayon et al. paper cited studies that demonstrated increased risk of negative outcomes such as asthma in C-section babies.
iii) Breastfeeding vs Formula- Breast milk contains many microbes in it which are introduced to the baby during breatfeeding. This provides an early microbiome to the child who otherwise would not have been exposed to the many microbes of a mature human. Additionally, increased contact with the mother is made during breastfeeding, furthering the effect.
iv) Antibiotic exposure- Mother and baby exposure to antibiotics will effect the newborn’s microbiome. Logically, this makes sense as taking antibiotics is known to lower diversity of microbes.