Children born by c-section are far more likely to be obese by the time they reach five years old, the biggest ever analysis of the health impacts of caesareans has found.

Researchers from the University of Edinburgh reviewed data from 80 studies and trials which jointly looked at 29 million births.

They found that the risk of obesity for under fives jumped by 59 per cent if they had been delivered through a c-section. The youngsters were also 21 per cent more likely to develop asthma by the age of 12.

Scientists said there was growing evidence that c-sections influence the development of the immune system and gut bacteria. And many women have the procedure because they themselves are obese, which also influences their baby’s health.

The review of studies, also found that women who had undergone a previous Caesarean were more likely to suffer pregnancy complications in the future. The change of future stillbirth rose by 17 per cent and miscarriage by 27 per cent.

However it did seem to protect women from urinary incontinence, lowering the chance of bladder control problems by 56 per cent.