Factors Affecting Gastrointestinal Microbiome Development in Neonates.

Plain Language Summary

This narrative review looks at factors affecting the development of the gastrointestinal (GI) microbiome, before, during and after birth. Animal studies suggest that composition and activity of the microbiome affects the structural and functional development of the GI tract. Although evidence is still limited, it is now believed that microbial colonisation starts in utero (before birth). Mode of birth, vaginal versus caesarean section (CS), appears to play an important role in the development of the gut microbiome and can lead to long-term metabolic and immunological consequences, including a higher risk for a number of conditions in those born by CS. Likewise, breast-feeding versus formula-feeding can affect the microbiome composition. These differences are attributed to both bacteria being transferred directly through breast milk and prebiotic factors in breast milk. Maternal and infant perinatal (during birth) exposure to antibiotics has been linked to an increased risk of several conditions, including asthma, obesity, inflammatory bowel disease and other allergic and inflammatory conditions in children. Other factors that appear to affect the development of the microbiome in infants include maternal lifestyle (e.g. rural versus urban), maternal diet, and environment, in particular, staying in a Neonatal Intensive Care Unit. A limitation the authors point out in comparing study results is that different techniques, both culture based and non-culture based, are used for determining the bacterial microflora.