The composition of gut microbiota in a newborn baby's gut has been linked to the rate of early infant growth, reports research published this week in PLOS Computational Biology. The findings support the assertion that the early development of "microbiota" -- the body's microbial ecosystem -- in an infant can influence growth and thereby the likelihood of obesity. The sterile（无菌的） gut of a new-born baby is quickly populated by a variety of different microbes. This study identified connections between different bacteria and both expected and reduced infant growth rates.

The study, set up at the Norwegian Institute of Public Health, by Principal Investigator Merete Eggesbo took data from infants when they were 4, 10, 30 and 120 days old. By looking at faecal samples from 218 babies, the statisticians Richard White and Shyamal Peddada developed a method aimed to identify the points and periods in time where the detection of specific bacterial groups was associated with an infant's development.

Their study showed that the detection of Bacteroides species at day 30 in males was significantly associated with reduced growth. In contrast the presence of E. coli species from four to 30 days after birth was observed to correspond with expected growth in both male and female infants.

The authors mapped part of infant gut microbiota using broad and unspecific probes only, thus the observed associations may be markers for other alterations in the gut microbiota composition. It is also possible that other factors early in life could give rise to such associations and the study may not have been large enough to adequately control for this. However, they believe their method can prove a useful tool for studying this intriguing（有趣的） topic further.

The authors comment: "We have created a new way of looking at the development of gut microbiota over time and relating this development to health outcomes. This is useful to the scientific community as it is difficult to characterise, in a meaningful way, how the gut develops over time. After applying our new method, we found an indication that the composition of early life gut microbiota may be associated with how fast or slow babies grow in early life although there is also the possibility that factors early in life affect both gut microbiota and how fast the baby grows"

Knowledge of how the optimal composition of gut microbiota develops over time is a prerequisite（先决条件） for any successful manipulation of gut microbiota.