Babies born by Caesarean section 'more likely to develop asthma'



Children born by Caesarean section are more likely to suffer from asthma

Babies delivered by Caesarean are at greater risk of asthma than those born naturally, warn researchers.

A new study will increase concern about the soaring rate of Caesareans, particularly for mothers who are 'too posh to push' and want the convenience of a planned operation.



Although emergency Caesarean births can be life-saving, planned surgery is recognised as riskier for mothers because they are more likely to develop complications and spend twice as long in hospital as women having a natural delivery.



But new research published today in the journal Thorax adds to worries about the hazards for infants.

It found babies delivered by Caesarean were 80 per cent more likely to be be diagnosed with asthma in childhood, compared with those born naturally.



Although the exact reasons are unknown, surgical babies may be missing out on hormonal and physiological changes that happen during labour which are necessary for the immune system and lungs to mature.



Previous research has linked elective Caesareans with an increased risk of respiratory difficulties in new-borns, but different studies have produced conflicting results.



However, Swiss doctors carrying out the latest study believe the findings are the strongest yet because more than 3,000 children were monitored for eight years.



The diagnosis of asthma also depended on the use of inhaled steroids, which meant borderline cases were excluded.



By the time they were were eight,12.4 per cent of children had been diagnosed with asthma.



Just 8.5 per cent of children had been born by Caesarean section, but they were almost 80 per cent more likely to have been diagnosed with the respiratory disease than those delivered vaginally.



The link was even stronger for around one in 10 children with two allergic parents, who were at a stronger inherited risk as a result.



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 per cent more likely to be diagnosed with asthma.



The latest findings come amid controversy over the rising number of Caesareans, with experts trying to cut the rate which is up to one in three in some parts of the country - twice the 15 per cent recommended by the World Health Organisation.



Fewer than half of all mothers in the UK have a completely natural birth, with 55 per cent requiring forceps, ventouse (suction cap) or a Caesarean to assist with delivery.

Dr Caroline Roduit, of Kinderspital Zurich, Universitats-Kinderlinik, Zurich, who led the study, said an increased risk of asthma may lie in the timing of the priming of the immune system to resist allergic disorders.

Caesarean delivery delays exposure to microbes that kick-start the immune system to respond to allergenic substances.



Dr Roduit said pregnant women should be fully informed about the possible extra risk to their child if they chose a Caesarean for 'social' reasons.

She said: 'The increased rate of Caesarean section is partly due to maternal demand with medical reason.



'In this situation the mother should be informed of the risk of asthma for her child, particularly when the parents have a history of allergy or asthma.'



Dr Mike Thomas, Chief Medical Adviser to Asthma UK charity, said: 'This study builds on previous evidence indicating that birth by Caesarean section may increase the risks of asthma, particularly in children whose parents have asthma or allergies.



'Sometimes a Caesarean section is needed for medical reasons, but where possible a natural birth is better.'



Last year a Danish study found a link between planned Caesareans and breathing problems in babies.



An Oxford University study found women could be four times more likely to die in childbirth if they opted for a Caesarean instead of natural birth.



The review of more than 94,000 births showed that women who had a planned Caesarean put themselves and their babies at increased risk of complications.



Known risks to the mother include bleeding and infection, while babies are more likely to need specialist care.