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.

Breastmilk contains many prebiotics to support the growth of beneficial bacteria in the infant’s gut.  It also contains bacteria that seed the infant’s gut.  Previous research has shown that the bacteria in breast milk do indeed take hold and colonize the gut, and so it is imperative to infant microbiome development.  An article published last week sought to discover if the breastmilk microbiome changes depending on mode of delivery, especially since we have seen that C-section infant’s have much different microbiomes than their vaginally delivered counterparts.  The scientists published their results in the journal Microbiome.

The scientists tested the breastmilk of 39 Canadian women.  Despite various backgrounds, each woman’s milk was dominated by Staphylococcus, Enterobacteriaceae, and Pseudomonas.  Moreover, there were not major differences in the breast milk microbiomes between modes of delivery, showing that it is not effected by C-section of vaginal birth.  In addition, the gender of the baby did not change the microbiome either.  Interestingly, the microbiomes were very different between mothers, meaning that babies are being exposed to highly diverse bacteria from milk.  In one case 80% of the bacteria were staphylococci, and in another case more than 50% was Pseudomonas.

There is little evidence that shows how differences in breast milk microbiomes are affecting children.  That said, we know the microbiome is critical to immune system development, and therefore it reasons that these differences may be important.  In any event, it is useful to see that mode of delivery itself is unlikely to change the breastmilk microbiome.

Operating room bacteria colonize infants’ guts after C-sections

Newborns are a great study subject in the field of microbiology, because scientists are still discovering how the microbiome develops and what factors affect it. In human infants, it has been proven that vaginal birth exposes infants to bacteria that are different from those received by the mother through C-section. Babies born by vaginal delivery have gut bacteria correlated with vaginal bacteria, while babies born by C-section have gut bacteria correlated with human skin bacteria. For babies born by C-section, the sources of the human skin microbes that are acquired are still unknown.  In a study published by Microbiome, a group of scientists tested the hypothesis that the operating room environment contains human skin bacteria that could be seeding the gut microbiome of C-section born babies.

To test their hypothesis, the researchers collected samples from 11 sites in four operating rooms from three hospitals in New York City, NY and San Juan, PR. Of the 44 operating room samples that were collected, 68% of the samples contained a sufficient number of bacterial DNA samples for sequence analysis. After analyzing the bacteria collected, it was found that all samples contained human skin bacteria, with Staphylococcus and Corynebacterium being the greatest in quantity. Lamps on the operating bed and baby crib showed higher abundances of these bacteria relative to the other sampling sites. The scientists confirmed that the samples collected were more similar to human skin microbiota than other body sites, by comparing the samples to oral, fecal, and vaginal database samples.       

Even though operating rooms are supposed to be spotlessly clean and germ-free, this study shows that there are still dust particles containing human skin, and therefore human skin microbiota, samples. These samples could be from people moving in and out of the operating room during a C-section, or it could come from the people cleaning the OR. Either way, the human skin bacteria in the operating room most-likely are what influences the infant’s developing gut microbiome. 

Gut bacteria may help prevent asthma in children

The world has seen an explosive rise in asthma over the past three decades. Such a rise in prevalence cannot be only a result of genetic variation and leads us to believe that environmental factors play an important role in this change. There are several possible explanations for this including what we call the “hygiene hypothesis”, or the idea that we now live in an environment that is too clean and we are no longer exposed to the bacteria and germs that earlier generations were exposed to. Another possible explanation is as the world changes and becomes more modern, these environmental changes are affecting our microbiome and the “normal” microbiome is shifting to a new normal.

To better understand why some children are at high risk for becoming asthmatic, scientists in Canada studied the microbiome of 319 children in the Canadian Healthy Infant Longitudinal Development (CHILD) Study. They sequenced fecal samples from the children and found that 4 groups of bacteria that were decreased in prevalence compared to the children without asthma. Bacteria from the genus Lachnospira, Veillonella, Faecalibacterium, and Rothia (FLVR) were at lower levels after 3 months for the children at high risk for asthma however over time, this leveled out and was similar to the children not at risk for asthma.

The study did not identify what exactly caused these differences as there could be several reasons for these differences including antibiotic use, the method in which the child was delivered either vaginally or by C-section, and if the child was breastfed or not. It is also possible and maybe even likely that some of the mother’s behaviors during the pregnancy such as diet could play an important role in the early development of the child’s microbiome.

The next obvious question is what can we do about this? Does this mean that we can now treat children that are deficient of these bacteria and they won’t get asthma? While it sounds simple, we don’t yet know too much about these bacteria and it will be important to better understand the impact his would have on the rest of development. Promising results from this study did show that when mice with low levels of FLVR were treated with probiotic samples of the bacteria, it protected them from getting asthma.

This is a very exciting study that may lead to new diagnostics for asthma and with more research and understanding, allow us to prevent the disease from developing. 

Elective vs. acute c-section deliveries: does it make a difference?

Caesarean sections are often needed when there are complications during a pregnancy or a woman often will elect to undergo a c-section due to a variety of reasons. In some nations, c-section delivery rates are incredibly high and there are attempts to lower these numbers. In Brazil for example, 85% of births in private hospitals are c-section deliveries. Babies born via C-section have been shown to have an increased risk of disease related to immune function. Previous studies had not discriminated against elective or acute c-sections and scientists in Denmark set out to do just that.

Conducting a population based study of 750,569 children born between January 1997 and December 2012, they analyzed children born via elective c-section, acute c-section, and those born vaginally as the reference. They found that the children born by either elective or acute c-section had a higher risk of asthma, laryngitis, and gastroenteritis though electively born c-section babies had a more pronounced risk than acute c-section babies. Those born via elective c-section had an increased risk of lower respiratory tract infection and juvenile idiopathic arthritis. Babies born by acute c-section had an increased risk of ulcerative colitis and celiac disease.

There were other factors not taken into account such as if the children were breastfed or if the mothers had asthma. While not everything was able to be taken into account, with such a large sample size, it is likely that the results from this study would not have been significantly affected by other factors. Most of the effects were seen in diseases that involved the mucosal immune system. The authors believe that the reason for the differences is a result of disturbed immune function as a result of differing microbial colonization in c-section babies.  

Vaginal microbiome once again tied to preterm birth

Preterm birth is major global health challenge.  Today, around 11% of all babies are born prior to 37 weeks, and are considered preterm.  Many of the causes of these preterm births are still unknown, but it is thought that around 25% of them may be related to a bacterial infection that comes from somewhere in the mother’s own body, i.e. her microbiome.  Many studies are now linking specific vaginal bacteria to risk of preterm birth, and other studies have even shown a connection between other microbiome sites, such as the gut and oral microbiome.  Unfortunately, studies on the microbiome and preterm birth are extremely difficult to conduct, so there are just not enough to have any sort of scientific consensus on the topic.  Last week though, a very rigorous study out f Stanford University was published in the Proceedings of the National Academy of Sciences that monitored expectant mothers vagina, gut, and oral microbiome throughout the course of her pregnancy and then for one year after.  Among many interesting findings, which are discussed below, the most important one was yet another connection between bacterial vaginosis and preterm birth.

The researchers monitored the vaginal, distal gut, salivary, and tooth/gum microbiomes of 49 women, 15 of which ended up delivering preterm, over the course of their pregnancy and for one year after.  Interestingly, the non-vaginal sites’ microbiomes remained relatively stable over the duration of the pregnancy, and even for the one year after.  The vaginal microbiome, however, did show some differences during and after pregnancy.

As many of our readers already know, a healthy vaginal flora is dominated by Lactobacilli, but around 20% of American women are dominated by other species, such as Gardnerella vaginalis, and have an overall increased vaginal diversity.  These women have what is known as community state type four, or CST4, and these women could be diagnosed with bacterial vaginosis (BV), though the clinical diagnosis is not so specific.  The other community state types, CST1, 2, 3, and 5, are dominated by different strains of Lactobacilli, and are generally regarded as healthy.  This current research showed that many of the women’s vaginal microbiomes actually shifted between various CST’s during pregnancy, most often shifting to and from CST4.  These transitions had no association with preterm birth, though.  After giving birth the vaginal microbiome became more diverse, and had greater abundances in anaerobic bacteria, such as Peptoniphilus, Prevotella, and Anaerococcus.  In addition, this usually coincided with a decrease in Lactobacilli.  Surprisingly, these changes did not seem to relate to mode of delivery (C-section of vaginal).

CST4 has been linked to preterm birth before, and this was reinforced in this study.  The scientists found that the longer a women’s vaginal microbiome was within CST4, the greater risk she had for preterm birth.  In addition, the abundance of Gardnerella and Ureaplasma, specifically, were linked to preterm birth.

This study reinforces what many microbiome scientists already suspect, and that is the importance of the vaginal flora in preterm birth.  It is unclear at this point if manipulating the vaginal flora prior to, or during pregnancy would help prevent preterm birth, but it is certainly worthy of discussion and clinical testing.  If you are reading this and wondering what your vaginal microbiome is, then we recommend you participate in the citizen science project, YourPrivateBiome, to find out.  You can learn more about it by following this link on our site, or just click the link above.