Babies born by Caesarean section or fed formula milk are at a higher risk of asthma, scientists fear.

London - Babies born by Caesarean section or fed formula milk are at a higher risk of asthma, scientists fear.

Researchers believe there is a link between key bacteria in a baby’s gut and their chances of developing the illness.

Those missing the bacteria – thought to be transferred from mother to child during birth or breastfeeding – at the age of three months were more than 20 times more likely to have been diagnosed with asthma at five.

It is believed exposure to these germs in the first months of life supercharges the immune system and helps prevent asthma from developing.

The UK has one of the highest asthma rates in Europe with 5.4 million sufferers – more than twice as many as 30 years ago. One in 11 children has asthma and the condition claims three lives a day, costing the NHS £1-billion a year.

While it isn’t clear where the bacteria that protects from asthma come from, one possible route is a transfer from mother to child during a natural birth. It is also thought breast milk contains nutrients that help “friendly bacteria” thrive. Babies born by C-section or fed formula milk may therefore be lacking in them, the Canadian researchers said.


Our high antibiotic use and “excessive” cleaning may also play a role in killing key bacteria, the journal Science Translational Medicine reports. This is known as the “hygiene hypothesis”, and suggests a bit of dirt helps strengthen our natural defences. In the study, scientists from the University of British Columbia, in Vancouver, tracked the health of more than 500 babies from birth until they turned five.

By analysing stool samples they found that children who did not have the bugs Faecalibacterium, Lachnospira, Veillonella and Rothia present in the gut at three months were 21.5 times more likely to have asthma aged five than those who did. The team said it might be possible to work out which babies are at risk of the condition by testing them for these four bugs at a few months old. Those deemed vulnerable could then be given the bacteria in the form of a probiotic drink.

Lead author Dr Brett Finlay said: “It shows that gut bacteria play a role in asthma, early in life when the baby’s immune system is being established.”

Fellow researcher Dr Stuart Turvey added: “This discovery gives us new potential ways to prevent this disease that is life-threatening for many children.”

Rosemary Dodds, of the National Childbirth Trust, said: “Asthma is a worrying and stressful condition ...Newer areas of research such as gut bacteria and the ‘hygiene hypothesis’ show links to asthma but there is still a lot which needs to be understood and parents need to know what they can do now.”