The human gut contains a diverse ecosystem of microbes: mainly bacteria, as well as viruses and fungi, termed the gut microbiota. Recent years have shown that the gut microbiota have widespread effects on the overall functioning of the host's body. Normally infants receive gut bacteria from the mother at birth. Some of these maternal bacteria grow out in the infant as they aid the infant in digesting breast milk.

Birth by Cesarean section (C-section) has been shown to be especially detrimental to normal gut microbiota development. During birth by C-section, infants are not exposed to maternal fecal microbes and this prevents the natural transfer of microbes from mother to baby.

In the recently reported study, researchers of mainly the University of Helsinki evaluated whether the disturbed intestinal microbiota development could be restored in term Cesarean section infants by postnatal, orally-delivered maternal fecal microbiota transplantation (FMT). FMT has been successfully used in adults to normalize gut microbiota composition and cure diseases such as recurrent Clostridium difficile infections.

The results of the study are published in the scientific journal Cell.

"Birth by C-section is associated with an increased risk of many immune-related diseases, suggesting that the lack of maternal microbes in early life may have long-term consequences on the health of the child. This proof-of-concept study demonstrates that the intestinal microbiota of infants born by C-section can be postnatally restored by maternal FMT and provides further support for the natural transfer of gut microbiota from mother to infant," says Willem M de Vos, Professor of Human Microbiomics who was a senior author on the study.

The procedure reduces risks that abnormal gut microbiota may confer

The researchers applied FMT immediately after birth by using the infants' own mothers' fecal samples. Because feces can contain dangerous pathogens, these were first carefully screened. Out of 17 tested mothers, 7 had pathogen-free samples and were selected for the study.

All seven C-section born infants that received the FMT remained healthy and experienced no negative effects from the treatment. Their gut microbiota composition was monitored for 3 months and compared the composition to that of untreated C-section born infants and vaginally born infants.

"The gut microbiota of the FMT-treated infants became very quickly similar to that of vaginally born infants. It did not resemble that of the untreated C-section born infants, showing that the treatment was effective in restoring normal microbiota development," says Dr. Katri Korpela, first author on the study.

"This simple procedure can normalize gut microbiota colonization and development in C-section born infants, which will likely contribute to reduced risk of developing chronic diseases that abnormal gut microbiota may confer," adds Dr. Otto Helve MD, specialist in pediatric infectious diseases and shared first author of the study.

"This procedure should be only performed after careful screening of the mother for potential pathogens," stresses Professor Sture Andersson MD, neonatologist who also was a senior author on the publication.