Children born by caesarean section may be more likely to become overweight or obese in adulthood, according to a new review of evidence.
Midwives said the findings were only the latest proof of the “negative implications” of caesareans, and urged women who did not need the procedure for medical reasons, not to take the decision to have one lightly.
The odds of being overweight or obese were 26 per cent higher for adults who had been born by caesarean, researchers from Imperial College London said, following an analysis of data from 15 studies with more than 38,000 participants.
Previous studies have also suggested a link between caesarean sections and an increased likelihood of diabetes later in life, although the reasons for the link are not fully understood.
However, Dr Matthew Hyde, one the researchers from Imperial’s Faculty of Medicine, said there were “plausible mechanisms” that might link caesarean births to increases in weight later in life.
“The types of healthy bacteria in the gut differ in babies born by caesarean and vaginal delivery, which can have broad effects on health,” he said. “Also the compression of the baby during vaginal birth appears to influence which genes are switched on, and this could have long-term effect on metabolism.”
Around a quarter to a third of all births in the UK are carried out by caesarean section and the rate is even higher in other countries. While some are medically necessary to avoid complications in vaginal delivery, an increasing number of women are choosing to have caesareans, often because of a phobia of childbirth that is believed to affect between six and 10 per cent of women.
The Royal College of Midwives said that that the new evidence of a link with unhealthy weight later in life should be reviewed by health professionals and discussed with women to help them make a decision.
Mervi Jokinen, the RCM’s practice and standards manager, said that caesareans were major surgical operations with an increased potential for complications.
“We would encourage women to think carefully and weigh up the evidence before they decide to have a non-urgent caesarean,” she said. “Women should also be aware that this is a major surgical operation that has the potential for increased complications every time a woman has the procedure carried out.”
New guidelines were issued in 2011 stating that women should have a caesarean section if they asked for it, even if it is not medically required. However, hospitals had been offering the procedures to women on this basis for many years by this time.