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C-section babies, bigger adults?

WebMD UK Health News
Medically Reviewed by Dr Rob Hicks

26th February 2014 – A new analysis by researchers from Imperial College London has found that babies born by caesarean section are more likely to be overweight or obese as adults.

It found that the odds of being overweight is 26% higher, and the odds of being obese 22% higher, for adults born by caesarean section than those born by vaginal delivery.

The authors say they can't be certain that caesarean delivery causes higher body weight, as the association may be explained by other factors that weren't recorded in the data they analysed.

The Royal College of Midwives says the analysis is Increasing evidence of the negative impacts of caesareans.


The World Health Organisation recommends that the c-section rate should not exceed 15%. Today almost 1 in 4 births (23.8%) in England are by caesarean section, around twice as many as in 1990. In some countries the rate is much higher, with 60% of mothers in China and almost half in Brazil having the procedure.

The researchers, say there are good reasons why many women should have a c-section, but mothers choosing a caesarean should be aware that there might be long-term consequences for their children.

Commenting on the research Mervi Jokinen, practice and standards development advisor at the Royal College of Midwives says: "There is increasing evidence about the negative implications for women and their babies of having a caesarean section. This research provides more information for health professionals to review and discuss with women. A decision to have a caesarean section should not be taken lightly by women or doctors.

"Whilst some caesarean sections are needed for medical reasons, many are not and we would encourage women to think carefully and weigh up the evidence before they decide to have a non-urgent caesarean. 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.

"The RCM therefore supports NICE guidelines which encourage women to have a thorough discussion with their obstetricians and midwives about the implications of having a caesarean section, especially in circumstances where other options remain open to them."

Other studies have suggested that the odds of other adverse long-term outcomes, such asthma and type 1 diabetes in childhood, are also higher in babies born by caesarean.

Large study

The new finding has been reported in the journal PLOS ONE. It is based on combined data from 15 studies, from 10 countries, spanning 4 continents

The analysis found that the average BMI of adults born by caesarean section is around half a unit more than those born by vaginal delivery. It is the largest study to show a link between caesarean delivery and BMI in adulthood.

Professor Neena Modi from the Department of Medicine at Imperial College and the report's senior author, says in a press statement: "We now need to determine whether this is the result of the C-section, or if other reasons explain the association.

Dr Matthew Hyde, one of the researchers, says in prepared statement: "There are plausible mechanisms by which caesarean delivery might influence later body weight. The types of healthy bacteria in the gut differ in babies born by caesarean and vaginal delivery, which can have broad effects on health. Also, the compression of the baby during vaginal birth appears to influence which genes are switched on, and this could have a long-term effect on metabolism."

Reviewed on February 27, 2014

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