What is a microbiome?

The following is a student blog post by Kim Sabin

What is a Microbiome?

   My name is Kim Sabin. I am the owner of Birthing Days. I am a Birth & Postpartum Doula, a Breastfeeding Educator, and a Bereavement Specialist. I am very passionate about helping women achieve the birth they desire to have.

              What is a microbiome? The word microbiome is defined as the collection of microbes or microorganisms that inhabit an environment, creating a sort of “mini-ecosystem”. Our human microbiome is made up of communities of symbiotic, commensal and pathogenic bacteria (along with fungi and viruses) all of which call our bodies home.

              Your body is part human and part microbe. Your human body consists of trillions of human cells and trillions of microorganisms. The microorganisms on and in your body, are: on your skin, in your mouth and lungs, up your nose, in your ears, in your eyes, in your vagina (if you are a woman), and in your gut.

              What do microbes do for human health? They help with human digestion, metabolism, manufacture vitamins, produce neurochemicals, interact with our hormones, interact with our nervous system, have anti-infective properties, and are integral to our immune system.  Microbes could also impact the brain. This happens through the gut-brain connection. This could impact our mood and behavior.

              Scientist have discovered that a person’s microbiomes are as unique as a fingerprint.

              You may be wondering what this has to do with childbirth. The mother’s unique microbiome is passed to the next generation through vaginal birth and exclusive breastfeeding. A mother’s microbiomes change during pregnancy. Changes accrue in the mother’s vaginal microbiome; more lactobacilli bacteria and changes accrue in the mother’s gut microbiome.


              Recent research indicates that the fetus could be exposed to a small amount of bacteria while in the womb. Baby is protected from most things by the amniotic sac. The sources in which the fetus could be exposed to the microbiomes are through the amniotic fluid, umbilical cord blood, fetal membranes, and the placenta.

              When the water breaks this marks the start of the main seeding event for founding the infant microbiomes. Every birth is different, so every baby will acquire a different set of microbes. During vaginal birth, baby is exposed to mother’s vaginal microbes in the birth canal. The mother’s vaginal bacteria enter the baby’s skin, eyes, ears, nose, and mouth. Some bacteria are swallowed as well. Once born baby acquires more microbes from mother’s gut (from contact with mother’s fecal matter), the air, every touch, skin-to-skin, and breastfeeding.

              Breastmilk provides everything a baby needs to survive and thrive. It provides nutrition, immune components, antibodies, anti-inflammatories, hormones, plus 700 species of microbes, and special sugar indigestible by baby. If sugars are indigestible by the baby, why are they there? They are meant for the baby’s microbes. The sugars feed the ‘right kind’ of bacteria acquired from the mother. Human milk oligosaccharides (HMO’s) in breast milk are special sugars. These special sugars feed the ‘right kind’ of bacteria acquired from the mother during vaginal birth and breastfeeding. These ‘right kinds’ of bacteria quickly colonize the infants gut to crowd out pathogens and to train infant’s immune system. As humans we have evolved the perfect ‘seed and feed’ process.

              Baby is born with an immune system. The bacteria in a baby’s gut help “train” the immune system to identify what is a “FRIEND” (to be tolerated) and what is a “FOE” (to be attacked). Ideally for optimal immune training, the right bacteria need to arrive in the right order and at the right time. There is only one chance for optimal immune training.

“There’s one chance; there’s a narrow window and if the maturation doesn’t happen then, the immune system is going to be out of balance, immature and respond haphazardly potentially for the rest of life.” – Rodney Dietert, Professor of Immunotoxicology at Cornell University.

              What about cesarean section babies or formula fed babies? Scientist believe that anything that interferes with ‘seeding and feeding’ of the infant microbiome could compromise the training of the baby’s immune system.

              “The single most important thing we can do for a healthy baby across a life course is to ensure that microbial seeding occurs completely at birth through vaginal delivery when possible, that skin-to-skin contact occurs, and that the microbes are supported through breastfeeding of significant duration. This should be on every birth plan.” -Rodney Dietert Professor of Immunotoxicology at Cornell University.

Reference: “Understanding the Infant Microbiome” Toni Harman https://microbirth.teachable.com/

All student article posts are the expressions of the student who wrote them. We do not take responsibility for the content, these are done as part of the educational experience and we try to encourage students to use their voice and learn to connect with clients through blogging and social media.
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