Caesarean section changes the newborn’s colonization – a link to disease risk?

Published Online: April 1, 2016

Delivery by Caesarean section (C-section) is a shared risk factor for several diseases in childhood, including asthma. During C-section the very first microbes colonizing the child are transferred from the environmental contacts and maternal skin rather than the mother’s birth canal. This points to the early bacterial composition of the newborn as an important factor for a healthy development, as the mode of delivery might determine, which microbes are the earliest colonizers of the human body.

In a study recently published in The Journal of Allergy and Clinical Immunology (JACI), Stokholm and colleagues determined the colonization patterns of the gut and airways of 700 children during the first year of life according to mode of delivery. The children participated in the Copenhagen Prospective Studies on Asthma in Childhood2010 (COPSAC2010) birth cohort, and had fecal samples collected at age 1 week, 1 month and 1 year as well as airway samples at age 1 week, 1 month and 3 months. These samples were all characterized by traditional culturing methods and the researchers examined bacterial differences between children born by natural delivery and by C-section, and furthermore between children who were born either by emergency or planned C-section.

In the study, 78% of the children were born by natural delivery, 12% by emergency and 9% by planned C-section. The researchers demonstrated major bacterial differences in the gut composition between natural delivery compared to Caesarean delivery, and furthermore also between planned and acute C-section. These differences were most obvious at 1 week of age, lesser at 1 month and no longer apparent at 1 year of age. The initial bacterial colonization of the airways was largely unaffected by birth mode.

The authors found that delivery by C-section was associated with changes in the early bacterial composition of the newborn’s gut but not of the airways. Interestingly, the observed differences were normalized at 1 year of age. If the microbial derangements after delivery by C-section are causal for later disease, this suggests a possible window of opportunity for modulation of disease trajectory in early life and predicts a possible target for future microbial manipulation.

The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

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