A new study examines the combined effects of different factors that have been previously linked to changes in gut bacteria in babies.
The research could be used to further understand the relationship between gut bacteria in infancy and health issues later in life, including allergies, asthma, weight problems or metabolic syndrome.
A team of researchers from several Canadian universities measured the rates at which various species of bacteria colonized or declined in the guts of infants exposed to various combinations of three different factors at birth: delivery through cesarean section, antibiotic treatments and formula feeding.
"We wanted to know about the combination effect, because these combinations are common," said the paper's senior author Anita Kozyrskyj. "For example, if you are delivered by cesarean, your mother always receives a dose of antibiotic prophylaxis, and those mothers often have difficulty breastfeeding."
Previous research has examined this relationship, but the new paper used statistical analysis to identify statistically significant changes in bacteria makeup from the age of 3 months to one year. In particular, Kozyrskyj and her colleagues were able to identify the rates at which the bacteria makeup changed in this crucial first year of the infants' lives.
All children undergo a series of changes in their guts from the moment they are born. The guts of children who are born without surgery, breastfed and not exposed to antibiotics all follow generally similar patterns of bacterial development.
From birth through the first few months of life, a category of bacteria known as Proteobacteria dominate in the gut. From about 3 to 6 months, they begin to decline and are followed by increasing numbers of bacteria in the Firmicutes and Bacteroidetes categories.
Kozyrskyj and her colleagues studied bacteria from the guts of 166 infants included in a large study known as the Canadian Healthy Infant Longitudinal Development (CHILD) study.
They sequenced the genes of the various bacterial strains and used a statistical analysis method called Significance Analysis of Microarrays to look for patterns in the genetic makeup at different points.
"All infants have this general pattern, but there are some deviations according to how you are delivered and how you are fed," Kozyrskyj told CNBC.
For example, vaginally born, formula-fed children, and children born through cesarean section did not see the same rate of decline of some types of Proteobacteria as others after three months.
In addition, the microbiota of infants born vaginally and exclusively formula fed were less enriched with some varieties of Firmicutes.
The researchers said these observed changes are relevant to the health of the children because they and others have previously shown gut bacteria populations to be associated with certain health conditions later on, ranging from food allergies, such as peanut allergies, to obesity and metabolic issues.
So for mothers who have to have cesarean sections for medical reasons? There are some areas of research that might be able to devise treatments to counteract these factors, Korzyskyj said. In the meantime, there is some evidence that suggests breastfeeding seems to correspond to reductions in these changes.