New research suggests that exposure to the vaginal microbiome during birth may not influence babies' gut microbiome as has long been assumed. A new study conducted by a team of Canadian scientists has revealed that the composition of the maternal vaginal microbiome has no significant influence on the microbiome composition found in infant stool during early life.
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Challenging the assumption that vaginal birth corresponds to better gut health for the baby
For many years, it has been strongly believed that vaginal birth, as opposed to birth by cesarean section, is beneficial to the baby's health. This is because it has been assumed that in moving through the vaginal microbiome, the baby is exposed to microbiota that influences the development of its own gut microbiome.
This assumption has been backed up by recent studies that have suggested that the mode of delivery significantly influences the gut microbiomes of babies and that those born by cesarean section are missing key microbes. A new study published in the journal Frontiers in Cellular and Infection Microbiology, however, has revealed evidence that contradicts this long-standing assumption.
No relationship found between vaginal microbiome composition and babies' stool microbiome
The study was one of the biggest ever mother-infant cohort studies. It recruited over 600 Canadian women expecting to give birth either vaginally or via cesarean section. Researchers took vaginal swabs from the mothers prior to delivery to assess their vaginal microbiome. Stool samples were also taken from the babies within 72 hours of birth, at 10 days old, and finally at three months old.
Analysis of the samples revealed that the mother's vaginal microbiome composition was not a predictor of the babies' stool microbiome composition at any of the three time points.
"It does not appear that exposure to maternal vaginal microbiota at the time of vaginal birth establishes the infant stool microbiome",
Dr. Deborah Money, Professor of Obstetrics, University of British Colombia
Scott Dos Santos, a PhD candidate at the University of Saskatchewan responsible for the study's lab work and data analysis, said, "from this study and other follow-up work, we were able to show that transfer of vaginal bacteria to the infant's gut is limited". It is theorized that other sources, such as the environment and breast milk, may play a more important role in establishing the baby's gut microbiome. Further research is needed to understand these potential relationships further.
The role of antibiotics on the microbiome
The study did find that at 10 days and three months, there were statistically significant differences between the stool microbiome composition of babies born vaginally compared with those born by cesarean section. Money hypothesizes that this difference might be related to antibiotic use "the differences we found between infants' stool microbiome composition by mode of delivery in early life seemed to be primarily influenced by exposure to antibiotics around the time of birth". However, more research is needed to fully understand the impact of antibiotics on the development of babies' gut microbiota.
More research is needed to understand the gut microbiome fully
Given the increasing importance attributed to the gut microbiome in the pathology of numerous diseases, it is vital that we understand the true relationship between the mode of birth and babies' gut microbiome.
More research is needed to further understand the findings of this study. Researchers pointed out its limitations in that stool microbiome samples were not collected from the mothers. Future studies that analyze this type of information may provide a valuable perspective. In addition, further studies are needed to explore the impact of antibiotic use on the development of the gut microbiome of infants.
Sources:
- Communications, F.S. (2023). Babies’ gut microbiome not influenced by mothers’ vaginal microbiome composition - Science & research news | Frontiers. [online] blog.frontiersin.org. Available at: https://blog.frontiersin.org/2023/03/30/maternal-vaginal-microbiome-composition-influence-baby/?utm_source=rss&utm_medium=rss&utm_campaign=maternal-vaginal-microbiome-composition-influence-baby#:~:text=Canadian%20researchers%20have%20examined%20this [Accessed 30 Mar. 2023].
- Callaway, E. (2019) "C-section babies are missing key microbes," Nature [Preprint]. Available at: https://doi.org/10.1038/d41586-019-02807-x.
- Chang, K.-C. et al. (2012) "Atomic Force Microscopy in biology and Biomedicine," Tzu Chi Medical Journal, 24(4), pp. 162–169. Available at: https://doi.org/10.1016/j.tcmj.2012.08.002.
- Shao, Y. et al. (2019) "Stunted microbiota and opportunistic pathogen colonization in caesarean-section birth," Nature, 574(7776), pp. 117–121. Available at: https://doi.org/10.1038/s41586-019-1560-1.
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