Sub-Journal of "Cell": Don't worry about the impact of cesarean section on baby's intestinal bacteria!

Are you born with intestinal bacteria? The colonization origin and development and evolution process of human intestinal flora has always attracted the attention of scientists
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Some studies have pointed out that during normal pregnancy, the newborn is sterile in the mother's womb [1,2]
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During childbirth, newborns obtain intestinal bacteria from their mother and the environment [3]
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It is not yet clear how the external environment affects the intestinal flora of pups [4]
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It is believed that the "priority effect" may have a long-term impact on the structure and function of the intestinal flora of infants and young children [5]
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The priority effect refers to the order in which the intestinal bacteria appear in the intestine, which means it is first come first served
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What happened during the development of the intestinal flora of human pups? Although there have been a series of studies on the intestinal flora of infants (0-3 years old), preschool children (3-6 years old) and school-age children (over 6 years old), there is still a lack of long-term, Multi-level longitudinal cohort study
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The development and evolution of human pups' intestinal flora to adult intestinal flora of different ages has not been fully studied
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Do whatever you want! Recently, Cell Host & Microbe published important research results from the Fredrik Bäckhed research group of Gothenburg University in Sweden, revealing the development trajectory of the intestinal flora of children aged 0-5 years [6]
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Researchers found that the trajectory of the development of the intestinal flora of children is similar, but the speed is different
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The intestinal flora of 5-year-old children is still developing and has not yet reached the level of complexity of adults
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At the same time, the late colonization of bacteria related to human health increases with the increase in the alpha diversity of the intestinal flora (richness of flora) in children and adults
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In addition, the study also found that although caesarean section has a greater impact on the intestinal flora in early childhood, this effect is gradually eliminated when children are 3-5 years old
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In this study, the researchers conducted a five-year longitudinal cohort study on the gut microbiota of 471 Swedish children (302 were born by normal birth and 169 were born by caesarean section)
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The five time points that the researchers sampled are 1 week (new born, NB), 4 months (4M), 12 months (12M), 3 years (3Y) and 5 years (5Y) after birth
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At the same time, the researchers also analyzed the gut microbiota (Mothers) of 357 postpartum mothers, and compared these data with the published gut microbiota data (S3WP) of 101 Swedish healthy adults
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With age, the abundance of children’s intestinal flora continues to increase.
Researchers have found that the alpha diversity of children’s intestinal flora (used to measure the abundance of the flora) increases with age, but still remains at 5 years of age.
Lower than adult level
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Interestingly, the study pointed out that factors such as birth method, gender, use of antibiotics at one year of age, and exclusive breastfeeding for the first 4 months after birth did not affect the alpha diversity of the gut microbiota
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At the same time, the structure of children's intestinal flora has changed significantly at different ages
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The older children are, the closer their intestinal flora is to adults, but there are still significant differences compared with adults at the age of 5 years
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The period of greatest changes in the structure of children's intestinal flora is 4 to 12 months, and the smallest changes are between 3 to 5 years old
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The development trajectory of the diversity of the intestinal flora of children of different ages The trajectory of the development of the intestinal flora of children is similar, and the speed is different.
In order to better characterize the dynamic change characteristics of the structure of the intestinal flora, the researcher will The trajectories are divided into four categories: ① The genera with the highest relative abundance at 4 months, such as Bifidobacterium and Lactobacillus; ② The genus with the highest relative abundance at 12 months, such as Eubacterium and Rumencoccus ( Ruminococcus); ③The genus whose relative abundance increased rapidly in 4-12 months and reached a stable level after 3 years, such as Bacteroides; ④The relative abundance increased after 12 months, and within 3 to 5 years Genera that continue to increase, such as Methanobrevibacter and Christensenellaceae
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Among them, Methanobrevibacter and Christensenellaceae appeared late and did not reach adult levels when children were 5 years old
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The structure and development trajectory of the intestinal flora in children of different ages.
The type of intestinal flora in children changes with age.
Researchers divided the intestinal flora samples into 14 types of bacteria
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Of these types, 3 are common in newborns (NB1-3), 4 are common in 4-month-old children (4M1-4), 3 are common in 12-month-old children (12M1-3), and 3 are common in 3-5 It is common in children aged 1 to 3 (Child1-3), and one species is common in adults
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The relative abundance of the genera in these flora types is also roughly consistent with their age change trajectories
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At the same time, the alpha diversity of the flora also shows the characteristics of increasing with age
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In addition, the researchers also observed that the growth rate of children's intestinal flora is not consistent
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The development speed of the intestinal flora of children of different ages is not consistent.
The difference in intestinal bacteria caused by caesarean section will gradually be closed.
Scientists have discovered that many factors affect the intestinal flora of our human pups and thus affect health
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These factors include the way of birth (normal delivery or caesarean section), the way of infant feeding (breast milk or formula feeding), etc.
[6]
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The researchers in this article found that the structure of the intestinal flora of newborns with different birth patterns and 4-month-old infants is significantly different, but with the increase of age, the structural differences between each other continue to decrease
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At 12 months of age, infants delivered by caesarean section have a higher proportion of low-diversity flora types (12M1 and 12M2)
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Surprisingly, at the age of 5, compared with normal children, the cesarean section has a higher bacterial flora diversity and a higher proportion of adult flora
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The above results indicate that the impact of normal delivery and caesarean section on children will be far-reaching.
Unfortunately, the researchers did not tell us whether the intestinal flora of children with different birth patterns is related to some health behaviors
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Summary of Changes in Intestinal Bacteria in Caesarean Section and Normal Childbirth with Growth This article has once again expanded my understanding of the intestinal flora
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I think this study has three major highlights: First, the biggest highlight of the study is the establishment of a 5-year-long longitudinal cohort of the intestinal flora of children, and further study of the developmental trajectory of the intestinal flora with age
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The saying goes well: a glimpse to get the whole picture, this article gave me the feeling of "getting the whole picture"
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Second, the study pointed out that different bacterial types in the intestinal flora have different developmental trajectories
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Many of the bacteria associated with adult health are only acquired when children are older
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At the same time, the study pointed out that the intestinal flora of 5-year-old children is still developing and has not yet reached the level of complexity of adults.

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Sure enough, our intestinal bacteria are also slowly growing up! Third, different birth methods do have an effect on the intestinal flora in early childhood, and this effect is gradually eliminated at the age of 3-5
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Human placenta has no microbiome but can contain potential pathogens [published correction appears in Nature.
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Fetal meconium does not have a detectable microbiota before birth [published online ahead of print, 2021 May 10].
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Mother -to-Infant Microbial Transmission from Different Body Sites Shapes the Developing Infant Gut Microbiome.
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001[5] Sprockett D, Fukami T, Relman DA.
Role of priority effects in the early-life assembly of the gut microbiota.
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173[6] Roswall J, Olsson LM, Kovatcheva-Datchary P, et al.
Developmental trajectory of the healthy human gut microbiota during the first 5 years of life.
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021 The author of this article | Jiang Yongmao Chief Editor | Dai Siyu2021.
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021 Author of this article | Jiang Yongmao Editor-in-Chief | Dai Siyu2021.
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021 Author of this article | Jiang Yongmao Editor-in-Chief | Dai Siyu