What is the microbiome?
The collection of bacteria, viruses, fungi, and other organisms that live in and on the body. We have about 10 trillion human cells in our bodies, and about 100 trillion microbes. We have evolved in tandem with this microbiome for thousands of years. The balance of microbiomes varies throughout our body, and the bacteria found in our mouths is different than on our skin, which is different than in our intestines.
Why does the microbiome matter?
- A balance of microbes leads to optimal health. An imbalance can lead to disease. For example, a vaginal yeast infection may occur when the healthy bacteria are reduced by antibiotics, allowing yeast to overgrow.
- Good bacteria can aid digestion, provide vitamins (K and B12), regulate the bowels, stimulate the development of the immune system, and protect against infection.
- An overgrowth of harmful bacteria can lead to infectious disease.
- Disruption of the gut microbiota has been linked to inflammatory bowel disease, diabetes, obesity, allergies, asthma, and some cancers.
- Many studies have shown that the presence of absence of specific microbes can cause life-long changes in immunity.
How does a baby’s microbiome develop?
- During pregnancy
- In the past, the womb was believed to be a sterile environment. However, microbes are found in the placenta, amniotic fluid, and in meconium. (The waste that accumulates in the fetal bowels.)
- Maternal fecal microbes have been found in the uterine environment, leading to hypotheses that microbes from throughout the body are transferred through the bloodstream. And from there into the placenta, then the umbilical cord and the amniotic fluid.
- Placental microbes are similar to the microbes in the mother’s mouth – especially types of bacteria that aid in the metabolism of food.
- Healthy bacteria may benefit baby. For example, if the mother lived or worked on a farm, that might protect against allergies and asthma.
- Others worry that unhealthy bacteria may affect baby. For example, obese women tend to have abnormal gut microbiota. This may be transferred to the baby.
- Maternal diet affects the baby. E. coli bacteria (an unhealthy bacteria) was less common amongst babies whose mothers ate primarily organic foods.
- At birth
- During a vaginal birth, a baby is exposed to the microbes in mother’s vagina. In the third trimester, these are especially high in lactobacilli, which help the baby to digest milk.
- When a baby is placed skin-to-skin on a parent, they are exposed to the parent’s skin microbiome. The baby’s skin, mouth, and digestive tract are “seeded” by whatever and whomever they first have contact with.
- Through feeding
- Breastmilk exposes the baby to more microbes. Several are gut microbes that influence digestion.
- Breastmilk contains sugars (oligosaccharides) which are not digestible by babies, and whose role appears to be to nourish / feed a healthy microbiome in baby’s gut. These are also referred to as prebiotics. By helping healthy bacteria to grow, there is less room for unhealthy bacteria.
- When solid food is introduced, the microbiome begins to evolve to a more adult-like combination of microbes.
- Through the environment
- As baby is held by various people, their microbiomes influence it.
- As the baby starts to explore his world, crawling on the floor, playing outdoors, petting animals, and putting everything in his mouth, his microbiome shifts and evolves, becoming quite diverse by age 3. The “hygiene hypothesis” states that babies who are exposed to more symbiotic organisms have lower risks of asthma and allergies, and stronger immune systems.
What can interfere with the establishment of a healthy microbiome?
- During pregnancy and labor
- Antibiotics given to mom can affect the mix of microbes in the placenta, amniotic fluid and vagina. This disrupted microbiome is inherited by the baby.
- At birth
- Babies born by cesarean, and thus not exposed to vaginal bacteria, are at increased risk of asthma, allergies, obesity, diabetes, and celiac disease. Studies comparing the microbiomes of vaginally born babies with those born via cesarean have shown differences in their gut bacteria as much as seven years after delivery. (Salminen)
- After cesarean birth, instead of skin-to-skin contact with the parents, the baby’s first exposures are to hospital bacteria and the bacteria of hospital staff. (Babies in NICU were found to be colonized by bacteria from the health care staff, from medical equipment, and from the counter-tops in the NICU. – Brooks)
- Newborn care
- After any birth, if baby is wrapped in a blanket, and placed on a clothed parent, rather than skin-to-skin, the transfer of skin microbes is not complete.
- Early baths remove / reduce protective vernix, vaginal microbiome, and baby’s own newly seeded skin microbiome. Those are replaced by hospital microbes.
- If baby is given antibiotics, it reduces microbial diversity, and the number of both harmful and helpful bacteria. The impact lasts over 8 weeks. The longer the duration of antibiotics, the harder it is for the microbiome to recover. Early use of antibiotics, or prolonged use, can have long-term side effects, increasing risk of obesity or inflammatory bowel disease in later life.
- Formula-fed babies (even those who just had short-term formula feeding in the first few days) had increased harmful bacteria and decreased helpful bacteria.
What can parents and health care providers do to foster a healthy microbiome?
- During pregnancy:
- A mother can increase exposure to diverse healthy bacteria. Taking probiotic supplements may improve gut diversity (for mom and baby), may reduce gestational diabetes, and may reduce risk of allergy and eczema for the baby. (Research cited in Collado) You can eat probiotic foods which introduce healthy bacteria, such as fermented foods and foods with live cultures. And you can eat prebiotics – foods with oligosaccharides which feed healthy bacteria – see the list at the end of this article. (Reed)
- Minimize exposure to unhealthy bacteria, such as food-borne illnesses.
- During pregnancy and labor: Minimize exposure to antibiotics. If they are needed, consider consuming probiotics or prebiotics after the course of antibiotics is complete.
- If baby will be delivered by cesarean, a baby’s initial seeding is from hospital bacteria and skin microbes rather than vaginal microbes. You can expose the baby to vaginal bacteria by swabbing. Although swabbing does not colonize the baby as well as vaginal birth, it helps. (Swabbed babies had twice as much maternal bacteria as babies who were born by cesarean but not swabbed. Babies who were born vaginally had six times as much maternal bacteria.) Here’s the process:
- Sample mom’s vagina: make sure the mother is HIV-negative, strep-B negative, and has an acid, lactobacillus-dominated vagina.
- Place sterile gauze in the mother’s vagina. Incubate gauze for one hour. Remove prior to surgery.
- After birth, wipe baby’s mouth, face and hands with the gauze.
- Note: If the caregiver will not do this procedure, the mother and partner can do it themselves.
- After birth, baby should go straight onto the mother’s body, skin-to-skin. (Consider bringing a blanket from home to cover baby, rather than using a hospital blanket.)
- In the first hours, encourage people other than the parents to look but not touch.
- Wait 24 hours after birth to bathe the baby.
- Feed baby only breastmilk for as long as possible.
- If a breastfeeding mother develops mastitis or a yeast infection, ask a lactation consultant about treatment with lactobacillus probiotics.
- Giving probiotics to a baby can treat antibiotic-induced diarrhea, prevent eczema, reduce colic symptoms, and possibly reduce obesity in later life. (Studies cited in Arrieta and Collado.)
- Let your child explore their world, with plenty of time outdoors, digging in gardens, and exposure to animals, both pets and animals at petting zoos.
- Offer your child diverse foods, including: fermented foods and foods with live cultures (Yogurt, buttermilk, sour cream, kefir, sauerkraut and other fermented vegetables, tempeh, miso, soy sauce, kimchi, dosas and sourdough breads, kombucha, etc.) and prebiotic foods that are high in oligosaccharides (onions, garlic, legumes, asparagus, starchy vegetables like sweet potatoes, squash, turnips, parsnips, beets, and plantains)
Note: While many of those recommendations are supported by scientific research, not all have been adequately researched.
Here is a 2 page handout of this information to share with clients.
- Aagard, et al (2014). The placenta harbors a unique microbiome. Science Translational Medicine. http://www.ncbi.nlm.nih.gov/pubmed/24848255
- Arrieta, MC, et al. 2014. The intestinal microbiome in early life: health and disease. Front Immunol. Sep
- 5; 5:427. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4155789/
- Azad MB, et al. 2013. Gut microbiota of healthy Canadian infants: profiles by mode of delivery and infant diet at 4 months. CMAJ. Mar 19;185(5):385‐94. http://www.cmaj.ca/content/185/5/385.long
- Brooks B, et al. 2014. Microbes in the neonatal intensive care unit resemble those found in the gut of premature infants. Microbiome. Jan 28;2(1):1. http://www.ncbi.nlm.nih.gov/pubmed/?term=Microbes+in+the+neonatal+intensive+care+unit+resemble+those+found+in+the+gut+of+premature+infants
- Canadian Medical Association Journal. (2013, February 11). Infant gut microbiota influenced by cesarean section and breastfeeding practices; may impact long‐term health. ScienceDaily. sciencedaily.com/releases/2013/02/130211134842.htm
- Collado, et al. (2012) Microbial ecology and host-microbiota interactions during early life stages. Gut Microbes. 3(4): 352-365. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3463493/
- Dominguez‐Bello MG. 2014. Restoring the Newborn Microbiota. Poster presentation American Society for Microbiology, Boston. (http://commonhealth.wbur.org/2014/06/birth‐canal‐bacteria‐c‐section)
- Grens, K. (2014). The maternal microbiome. The Scientist Magazine. 28(8), 46‐46.
- Kesser, C. L.Ac. (2014) What to do if you need to take antibiotics. (blog post) http://chriskresser.com/what-to-do-if-you-need-to-take-antibiotics/
- Salminen, et al. (2004) Influence of mode of delivery on gut microbiota composition in seven year old children. Gut. 53: 1388 – 1389. http://gut.bmj.com/content/53/9/1388.2.long
- Reed, Rachel, and Johnson-Cash, Jessie. (2015) The Human Microbiome: considerations for pregnancy, birth and early mothering (blog post) http://midwifethinking.com/2014/01/15/the-human-microbiome-considerations-for-pregnancy-birth-and-early-mothering/
- Silgalliss, Mara. (2015) Type of Birth Alters Baby’s Bacteria. (blog post) http://lactobacto.com/2015/01/09/type-of-birth-alters-babys-bacteria/
- Simkin, P. (2015) Maternity Care And The Microbiome: How Birth Practices Dictate Future Health. Conference presentation. http://www.goldmidwifery.com/pdf/handouts/2015/PennySimkin.pdf
To learn more about practically any topic related to the perinatal period, check out Pregnancy, Childbirth, and the Newborn: The Complete Guide.