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Numerous studies in the last decades have tried to determine which factors during pregnancy and the first years of life pose a risk for developing allergies . Among the possible parameters, the impact of cesarean section versus natural childbirth has been analyzed. A recent study provides new evidence.
The importance of the vaginal microbiota
There is increasing scientific evidence on the impact of the microbiota and the interaction of our immune system with a wide spectrum of pathogens, and how important it is for the proper development and functioning of our defenses. Although this communication is highly complex , some aspects are accepted in the community.
One of the cornerstones of immune system development is early exposure to pathogens and substances that shape and activate our defenses. In this context, the microbiota plays a fundamental role.
The microbiota is the set of microorganisms (bacteria, viruses, fungi) that inhabit our organisms and that shape our immune or even metabolic functions. The composition of the microbiota depends on the organ or tissue that we investigate. We do not have the same type of microorganisms on the skin as in the intestine or vagina .
Precisely the vaginal microbiota is thought to be a determining factor for the development of the newborn, since during a natural vaginal delivery, part of this microbiota is transferred from the mother to the baby .
Natural childbirth or caesarean section?
Through many studies comparing the appearance of allergies in babies born by caesarean section or by natural birth, it had been concluded that there was a greater risk when the newborn came into the world without receiving the mother’s vaginal microbiota .
However, a new study conducted by an Australian research group and recently published in the prestigious journal in the field of Allergy and Immunology, Journal of Allergy and Clinical Immunology: In Practice , provides evidence that there is no increased risk .
One of the limitations of studies conducted with pregnant women is the lack of appropriate controls, since, for ethical and moral reasons, the mother or the fetus should never be consciously put at risk during the study.
Therefore, most of the studies are retrospective in style, where the data is collected and analyzed once it has passed and does not allow decisions to be made about treatment or procedures, but simply an attempt is made to find explanations for the results obtained.
Another aspect to take into account, especially in cesarean sections , is that on many occasions this procedure is carried out due to risks or complications for the mother or the fetus . In this situation, it is possible that these risk factors directly or indirectly affect the development of allergies.
Caesarean section does not increase the risk of food allergies
In this study, they performed allergy skin tests on 2,045 one-year-old children, and the results were analyzed according to whether they had a natural delivery or a cesarean section . Of all the children in the study, 30% were delivered by cesarean section.
When comparing the presence of food allergies, they found a prevalence of 12.7% in children by cesarean section and 13% in children by vaginal delivery . This shows that there is no increased risk of food allergies due to cesarean delivery.
However, the diagnosis of allergies in these infants was made after the first twelve months of life. Although food allergies usually appear in the first months of life, it is possible that if the diagnosis window is extended , the percentages may vary .
Another factor to keep in mind is that this study is limited to testing for allergies to foods that include nuts, eggs, or milk. Other types of allergies such as atopic dermatitis , which can also occur in the first years of life, have been linked to cesarean delivery.
As this study does not analyze the risk of suffering from other allergies, it cannot be ruled out that natural childbirth presents a lower risk compared to cesarean section in relation to other allergies . In addition, it is known that atopic dermatitis greatly increases the risk of suffering from other allergies such as rhinitis or asthma.
It is clear that more studies are needed to identify the risks associated with the development of allergies during pregnancy, childbirth and the first years of life. Despite the limitations that can be found for studies with pregnant women, there are many possibilities to obtain valuable information from this important window of time for the development of the immune system.
References:
Currell et al. 2022. Mode of Birth Is Not Associated With Food Allergy Risk in Infants. J Allergy Clin Immunol Pract. doi: 010.1016/j.jaip.2022.03.031
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