Children born by Caesarean delivery are at increased risk for developing asthma, particularly if their parents have allergies, according to a report published this month.

C-section has been thought to be a risk factor for asthma, although the relationship is controversial, Dr H. A. Smit, from the National Institute for Public Health and the Environment in Bilthoven, the Netherlands, and colleagues note in the report.

Dr Smit’s team analysed data from 2917 children to assess the association between Caesarean delivery and asthma or allergies at eight years of age.

Overall, 362, or 12.4 per cent, of the children developed asthma at age eight, the researchers report, and 8.5 per cent had been delivered by C-section.

Overall, children delivered by C-section were 79 per cent more likely to develop asthma than children born vaginally, the investigators found. The association between C-section and asthma was even stronger for children born to one or two allergic parents than for children born to parents without allergies.

“Our results emphasise the importance of gene-environment interactions on the development of asthma in children,” Dr Smit and colleagues conclude.

“The increased rate of Cesarean section is partly due to maternal demand without medical reason. In this situation, the mother should be informed of the risk of asthma for her child, especially when the parents have a history of allergy or asthma,” they wrote.

Reuters Health

Source: Thorax, February 2009