Knowing how microbiota is established in the gut is a very important topic regarding epithelium maturation and immune system developpement. The early studies focused on the dynamic of the microbiota in infant aiming to understand homeostasy mecanisms.

The early life microbiota show a low diversity but an high variation in term of species abundance between infants. One of the basic question was to answer how much time is necessary to reach an high richness microbiota equivalent to adults. While pionneer studies had estimated the microbiota maturation between two and four years old, a recent study using high-throughput technology showed that microbiota is established around three years old.

The early life microbiota is impacted significantly by the birth delivery. The common feature between infants microbiota is the high presence of Bifidobacterium species in the first years of life, which declining with age.

While the dominant group microbiota remains stable in healthy adult, dominant groups from gut microbial community are changed quite rapidly. This time frame can constitued a target which would be possible to act in a way to prevent some immune diseases.