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A small and quite lively baby
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It is a question that has been the subject of intensive research for a long time: What influence does the type of birth have on the later health of the child - and which factors play the greatest role in this question?
In fact, scientists keep linking the caesarean section – also known as a sectio caesarea or sectio for short – to later illnesses such as allergies or diabetes.
Dutch researchers have now found in a study that the type of delivery influences the microbiome in the baby's intestines - and thus probably also the way in which the immune system reacts to certain vaccinations.
The work was published in the journal "Nature Communications" - a total of 120 healthy babies were observed in their first 12 or 18 months of life.
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In fact, babies born via C-section had fewer Bifidobacterium and Escherichia coli bacteria in their microbiome than babies born vaginally.
In addition, the C-section children developed a weaker immune response to the vaccinations against pneumococci and meningococci.
Using saliva samples, the researchers determined so-called IgG antibodies (immunoglobulin G) - these provide information on how strong the reaction to the vaccine is.
Previous studies had already observed that the composition of the intestinal bacteria at the time of vaccination is important for the immune response.
But what are the consequences of the fact that this is already relevant in the first few months of life and, according to the new study, is related to the type of delivery?
After all, according to current figures from the Federal Statistical Office, almost every third child is born by caesarean section - a rate that has almost doubled in the last 30 years.
Groups are difficult to compare
"The influence on the development of the microbiome and the associated long-term imprinting of the immune system are an argument against a caesarean section," says Michael Zemlin, Director of the Clinic for General Paediatrics and Neonatology at the Saarland University Hospital.
According to Zemlin, one can assume that the mode of birth also has a direct or indirect effect on many other protective immune responses.
However, there are always reasons for the decision to have a caesarean section - a factor that makes it difficult to compare naturally born children with caesarean children.
In the current study, the children who were delivered by caesarean section were born earlier than those who were born vaginally, were treated in the hospital longer and were breastfed for a significantly shorter time.
"All factors that can have a significant impact on the microbiome," says Zemlin.
In order to clarify the role of the many influencing factors independently of one another, the study would have to be designed many times larger, according to the Homburg pediatrician.
"If this finding can be confirmed by further analysis, microbiota-based supplementation approaches might be promising," says Maria Vehreschild, head of the infectiology focus at Medical Clinic II of the University Hospital Frankfurt.
She sees potential for the development of therapies that "can be given to newborns during the immune maturation phase in order to later achieve an optimal vaccination result".
Overall, according to the professor of infectiology, it is a study with potentially important clinical implications.
In contrast to other studies, a very early time window, well before the vaccinations were carried out, was chosen as the basis for the microbiome analyses.
"The maturation of the early childhood immune system takes place in this time window of around 100 days," says Vehreschild.
The point in time at which the microbiome influences the maturation of certain cells of the immune system is well before the vaccination and the subsequent measurable vaccination response.
"Even making this connection is a great strength of the analysis."
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