C-Section babies are no more likely to be obese than those born normally: Stockholm scientists rubbish claims after study of 100,000 teenage boys

  • Karolinska Institute study suggests C-section babies no more likely to be obese
  • Researchers found no link between obesity and caesarean in 100,000 teenagers
  • Instead said strongest link to obesity related to mother's BMI before pregnancy

Babies delivered by caesarean section are no more likely to grow up obese than those born naturally, a new study has found.

Earlier research had suggested that children born by caesarean section were more likely to be overweight because they missed out on bacteria in the birth canal which helps regulate metabolism in later life. 

The Karolinska Institute in Stockholm, however, has now found no link between obesity and surgical delivery in a study of around 100,000 teenage boys.

They instead found the strongest link to obesity was related to how much the mother weighed before she became pregnant. 

Babies delivered by caesarean section are no more likely to grow up obese than those born naturally, a new study has found (stock image)

Babies delivered by caesarean section are no more likely to grow up obese than those born naturally, a new study has found (stock image)

In the study, around one in 20 of teenagers born by C-section were found to be severely overweight, which was roughly the same proportion as those who came into the world vaginally. 

Dr Daniel Berglind, of the Department of Global Public Health at Karolinska Institute, Stockholm, said: 'We found no evidence to support a link between C-sections and the development of obesity.

'This tells us that how women give birth may not be an important factor in the origins of the global obesity epidemic.'

More than a quarter of babies born in the UK are delivered by caesarean section, which is a huge increase on a rate of one in ten 30 years ago.

This spike in the number of C-sections has sparked intense research into the long-term consequences of the health of babies delivered this way, said the researchers. 

In the Swedish study, published in PLOS Medicine, Dr Bergling and his colleagues compared the Body Mass Index of 97,291 male babies who were born between 1982 and 1987. 

They were divided into three groups depending on whether they were born naturally or through elective and non-elective C-section.

The study found 5.5 and 5.6 per cent of the men delivered via the latter two, respectively, were obese - compared to 4.9 per cent of the former.

Research previously found children born by C-section were more likely to be overweight because they missed out on bacteria in the birth canal which helps regulate metabolism

Research previously found children born by C-section were more likely to be overweight because they missed out on bacteria in the birth canal which helps regulate metabolism 

But researchers said the slightly higher obesity rate among those born by caesarean section was no longer present after other factors, including the mother's BMI before she became pregnant, were taken into account.  

Dr Viktor Ahlqvist, also of the Department of Global Health, said: 'Most of the association between C-section and obesity could be explained by maternal pre-pregnancy BMI.

'This suggests that heritability and foetal exposure to obese-causing factors in the womb are more important when assessing the risk of obesity in the offspring than the mode of delivery.'

The researchers' findings contradict a British study published in the same journal last year, which investigated data from 80 studies and trials involving 29 million births.  

It found the risk of obesity for under fives jumped by 59 per cent if they had been delivered by C-section. The children were also 21 per cent more likely to develop asthma by the age of 12.

The University of Edinburgh team said there was growing evidence that C-sections influence the development of the immune system and gut bacteria.

In 2016, a study of around 22,000 children found those born by C-section were 15 per cent more likely to be obese. 

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