A baby’s immune system develops through the education of microbes, mainly present in the gut microbiome, to decipher what cells are “friendly” and what cells are the “enemy”, or disease, and should be fought against. The crucial period for the development of a baby’s immune system, through the development of the baby’s gut microbiome, is between birth and 4 months of life. Bifidobacteria plays an important role in this crucial period. When a baby is born there is a transition period when the baby increasingly hosts beneficial bacteria, such as Bifidobacteria with bacterial DNA, as opposed to the baby only having human DNA in the gut microbiome. The Study found that this transition from predominantly bacterial microbes increases over time and occurs earlier in vaginal delivery babies than in C-section delivered babies. The Study also showed that after 16 hours after birth the bacterial DNA began to exceed the count of human DNA.