Caesarean section birth boosts asthma risk

Tuesday 2nd December 2008

Babies born by Caesarean section are more prone to asthma than babies delivered vaginally, suggests research published ahead of print in the journal Thorax.

The findings are based on almost 3,000 children, whose respiratory health was monitored until they reached the age of eight.

By the time the children were eight years old, 362 (12.4%) had been diagnosed with asthma for which they had been prescribed inhaled steroids.

Just 8.5% (247) children had been born by Caesarean section, but they were almost 80% more likely to have been diagnosed with asthma than their vaginally delivered peers.

The association was even stronger for the 9% of children with two allergic parents and therefore a strong inherited predisposition to the disease.

They were almost three times more likely to be asthmatic by the time they were eight, compared with children whose parents were not allergic, who were around 36% more likely to have this diagnosis.

Rates of asthma have soared in industrialised countries in parallel with a rise in Caesarean section births, which have increased from 5% in the 1970s to more than 30% in 2000.

The authors say that the link between Caesarean section births and an increased risk of asthma may lie in the timing of the priming of the immune system: Caesarean delivery delays exposure to microbes.

Previous studies investigating the link between asthma and Caesarean delivery have produced conflicting results.

But the authors say that the number of children included in the study, the long monitoring period, and the definition of asthma to include inhaled steroids, strengthens their findings.

"The increased rate of Caesarean section is partly due to maternal demand without medical reason," say the authors.

And they add: "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."

Thorax

Your comments (terms and conditions apply):

"Very interesting, but could other factors regarding the birth be significant? Less likely to breastfeed, CS babies more likely to be
premature etc ..." - Rozalind Peel, Lancaster

"I don't believe this as I had two kids, both delivered by CS. The reason they gave is the timing, and exposure to microbes. Well, my babies were exposed after six hours of delivery." - M Thomas

"I've got two children, a boy (2 years) and a girl (5 months). Both of them were born by Caesarean section. My daughter at the age of three months started coughing. Day to day, her coughing was getting worse even with cough medicine (Prospan). I took my daughter for her triple booster immunization and mentioned her cough to the doctor, who suggested asthma. He prescribed montelukast (Singulair) 4 mg each night continuously. After almost two months, I've noticed my daughter has improved; her coughing is slowing down and her lungs are more clear (less wheezy)." - Ismadi and Asliza, Kuala Lumpur

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