Babies born by caesarean section are more likely to struggle with their weight as adults, experts warn.
The biggest study of its kind found the odds of being overweight or obese were around 25 per cent higher for those born by C-section when compared with those delivered naturally.
The analysis of data on more than 150,000 births from four continents suggests some of the seeds of obesity are sown the moment a child enters the world.
The finding comes amid a record number of caesarean deliveries worldwide and the researchers, from Imperial College London, said mothers-to-be should be made aware of the link.
Data from 15 studies carried out in ten different countries, including the UK, showed that the odds of being overweight are 26 per cent higher for babies born by C-section, while the odds of being obese are 22 per cent higher.
These adults are also, on average, half a BMI point heavier than those delivered naturally.
This equates to around 3lb of extra weight for a 5ft4in woman, or 4lb of extra weight for a 5ft10in man.
The number of C-sections in England has doubled in 30 years, with around one in four babies now born this way. The figure is as high as 50 per cent in some private hospitals.
The increase is blamed on a number of factors, from a society that is averse to pain, to older mothers enduring difficult births. Women who are ‘too posh to push’ – or request the surgery for non-medical reasons – account for about 7 per cent of the figure.
Obesity is also on the rise, with only around a third of adults in England at a healthy weight.
The study’s senior author, Professor Neena Modi, said: ‘There are good reasons why C-section may be the best option for many mothers and their babies, and C- sections can on occasion be life-saving.
‘However, we need to understand the long-term outcomes in order to provide the best advice to women who are considering caesarean delivery. This study shows that babies born by C-section are more likely to be overweight or obese later in life.
‘We now need to determine whether this is the result of the C-section, or if other reasons explain the association.’
The link between C-section delivery and obesity may be because bigger babies are more likely to be born by caesarean.
Women who have the procedure are also less likely to breastfeed, which could raise the risk of their child piling on the pounds when it gets older.