[메디게이트뉴스] Humans live in a sterile state in the womb, and after being exposed to microorganisms from birth, the development of the intestinal microbiota begins. However, during pregnancy, the fetus is also affected by the mother’s health status, so the influence of symbiotic bacteria on the human development process can be said to begin immediately after pregnancy through the mother.
Recently, there have been reports of the presence of microorganisms in the uterus, but it has not yet been accepted as orthodox, because the results of these studies are presumed to be due to contamination of the examination process. It is a well-known fact that during pregnancy, systemic or uterine inflammation and infection of the mother cause impaired growth of the fetus. Substituting this relationship into the aspect of the gut microbiota, maternal dysbiosis is highly likely to be associated with not only maternal health but also fetal growth delay or premature birth, just as dysbiosis is associated with various diseases in adults.
Recently, studies on the relationship between the intestinal microbiota and vaginal microbiota between premature birth and maternal have been reported using the 16S rRNA assay. Premature birth in high-income countries is associated with a decrease in maternal gut microbiota diversity and low intestinal abundance of Bifidobacterium, Streptococcus, and Clostridium. In addition, the vaginal microbiota of a mother is first encountered when a newborn is born, but it has recently been reported that it affects the health of the fetus by affecting the uterus during pregnancy.
In the case of dysbiosis such as vaginal bacteriosis, pathogens can easily penetrate into the uterus, causing inflammation, causing delayed growth in the uterus or premature birth. Lactobacillus is dominant in the quality of mothers in high-income countries, while Lactobacillus is deficient in the quality of mothers in underdeveloped countries such as Malawi, and Prevotella spp., Gemella spp. Corynebacterium spp. predominates, which is associated with small newborns. Therefore, it can be said that the role of the mother’s gut microbiota and vaginal microbiota is important to the health of the fetus or newborn immediately after birth.
Which microorganisms are initially exposed to during birth is a decisive factor affecting the initial formation of the gut microbiota. Therefore, when born with vaginal delivery and when born by cesarean section, the types of bacteria that begin to settle in the intestine are different. Children born with vaginal delivery are first exposed to fungi in the mother’s birth canal and Bifidobacterium is present in the feces, whereas children born with cesarean section are first exposed to skin fungi and pathogenic and inflammatory fungi such as Klebsiella and Enterococcus in the feces. Are more prevalent.
100 days after birth is an important time when human metabolic function, endocrine system, nervous system, immune system, etc. mature. At this time, the gut microbiota plays an essential role in the development of these functions. For this reason, the delay in the establishment of Bifidobacterium in the intestine after being born by cesarean section affects the future health status including the development of immunity in newborns. Recently, as it has been known that the gut microbiota plays an important role in the development of brain function, dysbiosis is believed to be a cause of developmental disorders such as hyperactivity syndrome and autism spectrum disease.
In the process of developing intestinal microbes immediately after birth, which bacteria are settled first and in what order are settled depends on the individual, and the composition of the intestinal microflora is affected accordingly. Normally, in the intestine of newborns, facultative anaerobes first settle and then obligate anaerobes such as Bifidobacterium, Bacteroides, and Clostridium increase during the first 6 months. At this time, the diversity of the intestinal microbiota is lower than that of adults, because the microbiota optimized for metabolism of human milk oligosaccharide (HMO), which is the main diet of newborns, is dominated. The main gut bacteria that characterize this period are Bifidobacterium longum or Streptococcus thermophilus.
In newborns fed mother’s milk, which are genetically high in HMOs, the intestinal bidifobacterium is more abundant. The HMO contained in breast milk plays an important role in the formation of the intestinal microbiota in newborns, thereby affecting childhood growth. Until now, the importance of breast milk has been emphasized for a variety of reasons, but in terms of the formation of the gut microbiota and the resulting impact on health, its importance becomes even greater. In addition, various microorganisms exist in breast milk, and it is known that about 25 to 30% of the neonatal flora originate from breast milk. Microorganisms in breast milk have a unique composition different from skin and berries and are affected by the mother’s weight or birth pattern, but are usually composed of Proteobacteria (mainly Pseudomonas), Staphylococcus, and Streptococcus.
In this way, the composition of the intestinal microbiota differs depending on the birth method and the lactation method, but from the beginning of eating baby food, it is no longer possible to observe the difference according to the birth method or the lactation method with a general test method. The intestinal microbiota formed immediately after birth changes its structure and function to the solid form from 6 months after the start of eating solid food, and gradually develops similar to that of adults.
Intestinal microbiota, which was previously optimized for HMO metabolism, decomposes glucan, mucin, and complex carbohydrates, and bacteria with the function of producing short chain fatty acids gradually become dominant. From this time on, what kind of food you eat and how much proper nutrition is maintained are factors that have the greatest influence on your gut microbiota. Therefore, poor nutritional status in infancy has a great influence on the formation and development of the intestinal microbiota, which becomes a factor that determines future health.
If you summarize the process of changes in the intestinal flora throughout the life, the intestinal flora is established with birth and gradually begins to develop, and the diversity increases to a level similar to that of adults around the age of 3 years. Due to the difference in sex hormones during puberty, there is a slight difference in composition between men and women, but the effect of sex is diluted during adulthood, so there is no significant difference. The gut microbiota in adulthood can be affected by various factors such as diet, bowel movement performance, stress, infection, drugs, and weight. After the onset of aging, the elderly become more vulnerable than the healthy gut microbiota in adulthood due to decreased diversity due to immune aging (Immunosenescence) or decreased physiological functions of the gastrointestinal tract. (Drawing)
In conclusion, 1000 days after pregnancy is the time when intestinal microbiota is formed. At this time, which gut microbiota is formed will affect the health of infants and infants and adults. Therefore, it can be said that this period is crucial for the health of both intestinal microflora and humans. Considering the maternal health, the birth pattern of the newborn, breastfeeding after birth, and diet, which mutually influence this process, efforts should be made to establish a good gut microbiota.
※The column is the columnist’s personal opinion and may not match the editorial direction of this magazine.