Caesarean section raises the asthma risk

Author:  Shrestha Suvash
Date:  November 2007

Caesarean section raises the risk of asthma by 20% and this might be the reason behind the increasing incidence of asthma these days, Dr. Suren Thavagnanam and his colleagues at the Royal Belfast Hospital for sick children in Northern Ireland concluded in their meta-analysis report published in Clinical and Experimental Allergy, July 2007.

Babies born naturally are exposed to maternal vaginal bacteria that boost the babies' immune system. According to the so-called "Hygiene hypothesis", in the absence of such exposure, the immune system becomes over-sensitized to harmless materials like dust or pollen resulting in conditions like allergies and asthma.

"Too hygienic a birth without a welcome dose of mother's microbes might give rise to a hypersensitive future in a genetically susceptible baby," explains allergist Maria Pesonen of Helsinki Skin And Allergy Hospital in Finland. "Perhaps we should consider counterbalancing the lack of bacterial exposure in caesarean sections by using probiotics."

Many researchers have tested the link between caesarean section and asthma in the past but have not been able to produce a definite statement about the link. So, in the meta-analysis, Thavagnanam reviewed 22 previous studies and concluded that caesarean section really raises the risk of asthma in babies by about 20%. However, Pesonen is a little suspicious of the results and argues that the meta-analysis can give misleading results if the studies being compared have different methodologies, which makes them unsuitable for direct comparison.

In the UK, the present incidence of asthma is more than four times what it was in 1973. Besides caesarean section, this increase in incidence has been attributed to other factors as well, such as the increase in the rate of diagnosis; the decrease in other parasites and diseases, which causes the immune system to develop inappropriately; changes in breast feeding duration after birth and the chemicals used in manufactured milk.

Written by Suvash Shrestha

Reviewed by Matthew Getz

Published by Pooja Ghatalia.