What happens if you give c-section babies a vaginal microbiome?

Babies born by cesarian section have greater likelihoods of autoimmune diseases during childhood and later in life.  They also have a gut microbiome that resembles their mother’s skin right after birth. On the other hand, babies that are born vaginally have a gut microbiome that resembles their mothers’ vaginas, and are at lower risk for asthma and allergies.  Given the importance of the microbiome on immune development, many scientists believe that there may be a link between mode of delivery, the initial infant gut microbiome, and normal immune development.

One possible method to ensure a baby that is born by c-section is initially colonized by his or her mother’s vaginal microbiome is to swab the mother’s vagina and transfer her microbiome to the baby immediately after birth.  Researchers from New York University performed this exact experiment, and measured the changes that occurred in the gut after this intervention.  They published their results in the journal Nature Medicine.

In the study, 18 women were split into 3 groups: 7 women gave birth naturally, 7 women gave birth by c-section, and 4 women gave birth by c-section but had their vaginal flora transferred to the babies.  This last group of women had their vaginas screened for pathogens shortly before birth.  After the c-section, and within 2 minutes after, gauze was rubbed in the new mothers’ vaginas and then rubbed all over babies’ mouths, faces, and bodies.  The babies’ skin and gut microbiomes were measured and compared to the other two groups.  As expected, the babies born vaginally had microbiomes that resembled their mothers’ vaginas, and the babies born by c-section had microbiomes that resembled their mothers’ skin.  Interestingly, the c-section babies that were inoculated with their mothers’ vaginal microbiomes, had a microbiome that closely resembled their mothers’ vaginas, even after 1 month.  In addition, there were no adverse consequences to the microbiome transfer.

This was a small proof of concept study that successfully showed a vaginal microbiome transfer to c-section babies could properly colonize a newly born infant.  Further studies still need to confirm that the skin microbiome is unhealthy for a c-section baby, but if it is, then these vaginal flora inoculations may become a critical procedure to ensure a healthy immune system for all newborn infants.

New research shows that Bifidobacteria transfer from mother to child

Both natural birth (as opposed to birth by C-section) and breastfeeding are topics that stir up a lot of conversation among mothers and the scientific community. For example, there is the question of whether breastfeeding rather than formula feeding has some specific benefit to an infant’s health. Well, what about the infant’s gut microbial health? A new article published by Applied and Environmental Microbiology takes a look at whether natural birth and breastfeeding coincides with an exchange of bacteria from mother to child.

Four mother and infant pairs were included in the study that was meant to discover whether the mother transfers any bacterial strains to the infant during vaginal birth and breastfeeding. In particular, the scientists were looking at the genus Bifidobacterium because this group has been known to be early colonizers of the infant gut. In addition, this genus has specific ways of digesting a human mother’s milk. Mother-infant pairs 2 and 4 exclusively breastfed, while pairs 1 and 3 supplemented with formula. Milk samples were collected from the mothers and fecal samples were collected from the mothers and children.

After sequencing the bacteria, B. adolescentis, B. angulatum, B. breve, B. dentitum, B. pseudolongum and B. thermacidophilum were found to be common between all of the mother and the infant fecal samples. The scientists then looked to see which bacteria were in both the mother’s milk and the infant’s fecal sample. The results suggest that the milk may be responsible for transferring B. adolescentis, B. angulatum, B. breve, B. longum and B. pseudolongum to the infant. Interestingly, there were also some bifidobacteria strains that were unique to the infant, suggesting that either they went undetected in the mother or that the infant was exposed to this bacteria from somewhere else.

After six months, samples were collected again in order to see how/if the sample compositions change. The scientists found that, especially in the infants, the abundance of bifidobacteria decreases. This is most likely due to changes in diet – less breastfeeding and more formula feeding – and perhaps environmental exposure. All in all, the results of this experiment shows that the infant microbiome might indeed be influenced by a vertical transfer of bacteria from mother to child. With more evidence of this as a possibility, science may begin looking into more complete analyses with larger study sizes.  

Pregnancy and the microbiome

There have been a number of studies that discuss the importance of the microbiome transfer between mother and child; however few studies have looked into the changes that occur to the mother's vaginal microbiome during pregnancy.

A new paper published in the journal Microbiome by AMI Scientific Advisory Board member Dr. Jacques Ravel of the University of Maryland School of Medicine presents a longitudinal study of the vaginal microbiome of women during the course of pregnancy and compared that with women who were not pregnant.  The overall findings of the study conclude that there are statistically significant differences in the vaginal bacterial populations between pregnant and non-pregnant women.  Furthermore, the microbiome of pregnant women was more stable in non-pregnant women.

While there is a difference in the microbiome between pregnant and non-pregnant women, the authors stress that this difference in microbiomes may NOT be exclusive to pregnancy; therefore  at this point, not suitable for diagnostic purposes (say determining pregancy).  Furthermore, it is not known if these differences in any way benefit pregnant women or are just the result of different vaginal environments, for example higher estrogen levels in the vagina.

Finally, another paper that was possibly from the same longitudinal study showed no statistical connection between the vaginal microbiomes of women who go into pre-term labor and those who carry their child full term.