Figure 2.

The infant gut bacterial microbiome rapidly diversifies over the first year of life in healthy infants but is delayed in those who develop allergy or asthma or who are malnourished. A number of pre-, peri-, and postnatal environmental exposures are known to modulate risk for childhood disease, e.g., formula feeding, antimicrobial use, and exposure to environmental tobacco smoke (ETS) or animals. These same exposures also relate to gut microbiome composition at discrete developmental time points and to successional trajectories in early life.