Infants' Microbiome Impacted by Delivery, Feeding Methods

The gut microbe composition of infants who are six weeks old depends on their birth delivery method and how they are fed, suggests findings published in JAMA Pediatrics.

Researchers from the Geisel School of Medicine at Dartmouth observed 102 infants who were approximately 40 weeks to determine the associations of delivery mode and feeding methods with infant intestinal microbiome composition at about six weeks of life.

The researchers noted that the feeding method was already known to impact babies gut microbes, but they wanted to examine if the delivery method mattered beyond the first few days of an infant’s life.

Information about feeding was collected through detailed questionnaires prior to the time of stool collection. Of the total patients, 70 were exclusively breastfed, 26 received combination breastfeeding and formula, and six were exclusively fed formula. The researchers pulled delivery mode data from medical records: they determined that 70 babies were delivered vaginally and 32 were born via cesarean section.

The babies’ microbiomes were similar if they were fed exclusively formula or a combination formula and breast milk diet.

Babies fed exclusively breast milk had microbiomes that were distinct from other infants, compared to the patients who were fed only formula or the combination diet.

“Understanding the patterns of microbial colonization of the intestinal tract of healthy infants is critical for determining the health effects of specific alterable early life risk factors and exposures,” the authors said. “To this end, we have identified measurable differences in microbial communities in the intestinal tracts of infants according to their delivery mode and diet, with possible consequences for both short- and long term health.”

The authors added that they didn’t consider the infants’ diets and timing in the study, even though they did categorize the feeding practices, which could limit the findings of their study. Another limitation, they said, is their relatively small sample size, which constricts the application to a wider population in the US.

“The infant intestinal microbiome at approximately six weeks of age is significantly associated with both delivery mode and feeding method, and the supplementation of breast milk feeding with formula is associated with a microbiome composition that resembles that of infants who are exclusively formula fed,” the authors concluded. “These results may inform feeding choices and shed light on the mechanisms behind the lifelong health consequences of delivery and infant feeding modalities.”