Microbes in new babies depends on how they were born

A large study has identified important differences in the composition of the intestinal microbiome of newborns, depending on whether they were born with natural or cesarean delivery.

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Children who are born by cesarean section have an altered intestinal flora, in which potentially dangerous microbes are also present. It is the conclusion of a study, one of the largest carried out so far on the subject, published in the Journal Nature.

This apparently alarming conclusion is actually explained and contextualized. It has long been known that the intestinal bacterial flora , the composition of the so-called microbiome , exerts a considerable influence on the health of the organism, even on organs and functions that apparently have nothing to do with the intestine or digestion. The field of research that studies these topics is very recent, and has undergone explosive growth of interest and publications in recent years.

One of the questions that the researchers ask is how contact with these bacteria comes about for the first time, which will then accompany us throughout life. Given that the fetus develops in the sterile environment of the uterus. Various studies have suggested that the newborn acquires bacteria from its mother during the passage in the birth canal.

For children born with cesarean section, the absence of this initial "contamination" would result, according to some studies, of alterations, and also of possible consequences on health, for example in the development of the immune system, perhaps in the risk of certain disorders such as asthma, allergies, or even diabetes. All this, however, has yet to be proven.

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GOOD AND LESS GOOD

The new study, conducted by British researchers from the Wellcome Sanger Institute and other British research institutions, essentially confirms the hypothesis that the mode of childbirth is a determining factor in the acquisition of the microbiome. By analyzing the composition of the intestinal microbiome of nearly 600 children born in foreign hospitals through stool samples, the researchers observed that in those born with cesarean section, pathogenic and drug-resistant bacteria were more often present, probably acquired in the hospital environment.

The children born with natural childbirth seemed, on the other hand, more protected by these microbes, present in only 49 percent of the cases against 83 percent of those born with cesarean section. And their intestine was instead populated by other types of "good" microorganisms.

The sequencing of the genome of bacteria, in particular, showed that the most common species in babies born with natural births were bifidobacteria, those of the genus Escherichia or Bacteroides. On the contrary, these species were little present in the intestines of children born with cesarean, which abounded instead of microbes such as Enterococcus faecalis , Staphylococcus epidermis , Klebsiella, all common bacteria in the hospital environment and often a potential source of infection for very premature infants. The same alteration, although to a lesser extent, has been observed in naturally-born children, whose mother however had had prophylaxis with antibiotics during childbirth, or in breast-fed infants.

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TO BE TAKEN WITH THE SPRINGS

Another important observation of the new study is that the bacteria acquired by naturally-born children coincide for the most part with those of the mother, but not with the vaginal microbes, but with those of the intestine. This was a discovery not entirely expected and that could lead to rethinking certain practices recommended in recent years, especially in the Anglo-Saxon environment and on the basis of the first studies of this type, such as to buffer children born with cesarean section with gauze soaked in secretions vaginal discharge from the mother: they could be of no use or, worse, be harmful.

An important consideration is that in reality we still know very little about whether and how the observed differences and alterations can have consequences, in terms of health, on children or later in life. To understand this, many other studies will be needed. Another important point to make is that, as one of the authors stated, "the observed differences largely disappear over time". Already six to nine months after birth, the microbiome of children born with natural or cesarean delivery does not present substantial differences.

Reference for Further Reading

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