Caesarean Births

As a scientist, I have learned to look at the evidence, but also to consider the mechanisms and causes for effects. Sometimes, the evidence can point in different – and sometimes non-obvious – directions. So, for example, I’ve always been wary of evidence that babies born by Caesarean section are at greater risk of negative medical outcomes, including asthma or rhinitis. The reason for my wariness is that I just can’t see a plausible mechanism for a causal link between the birth method and the later medical condition.

But I’m now having to accept that there is such a link, and that birth by Caesarean section is accompanied by long-term physical effects. The most recent research among 1,255 babies and their mothers, reported in The Archives of Diseases in Childhood, shows that by the age of three more than one in seven children born by Caesarean section is obese, more than double the proportion among children born normally.

And there is now some evidence that the normal birth process results in changes to the make-up of the gut bacteria in babies, so my scepticism about causal links is reduced.

I’m always reluctant to extrapolate too far, but with more than 65,000 elective Caesarean sections in the England every year, that might mean more than 5,000 children at risk of or becoming obese by age three.