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0811 Risk of atopic disease and diabetes after caesarean section
A concept that has been around for some years is that there is an increased risk of developing atopic disease including asthma in children born by caesarean section. Several meta-analyses have been carried out, with some 20 studies meeting inclusion criteria, and results fairly consistently show that the risk of asthma is increased by around 20% when compared with the risk in children born vaginally. The number of studies meeting inclusion criteria is smaller when one looks at atopic disease, however the risks are of similar or higher magnitude for food allergy and allergic rhinitis, but not for eczema/atopic dermatitis. The proposed mechanism is via an altered bacterial colonization of the gut after caesarean section, and increased risk of developing asthma “under the hygiene hypothesis.” Indeed, when a Swedish group studied children born by caesarean section and compared outcomes to those born vaginally, there was a 30% increase in the risk of being hospitalized for asthma after operative delivery and a similar risk for being hospitalized for gastroenteritis. Along the same line of research, an increased risk has also been noted in the case of type 1 diabetes (again ~20+ percent above the risk associated with normal delivery) even after controlling for obvious confounders such as birthweight and gestation. However, a meta-analysis of the association between diabetes and asthma (unrelated to mode of delivery), while showing a significant relationship, found it to be an inverse one, i.e. there was a ±20 decrease in the risk of asthma in type 1 diabetics. While these results are of interest, and particularly taking into account the increase in caesarean section rates in many countries, the 20% increase in the risk of asthma after caesarean section does not explain the “allergy epidemic” that has been reported in recent literature.
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Clin Exp Allergy 2008; 38: 629-33 and 634-42
Diabetologia 2008; Feb 22 Epub ahead of print
Clin Exp Allergy 2003; 33: 757-64 |