Research published in the Archives of Disease in Childhood found just under 16% of children delivered via caesarean were obese by the age of three compared with 7.5% of those born vaginally.
Children delivered by c-section also had higher BMI and skinfold thickness measurements by the age of three.
The authors based their findings on 1,255 mother and child pairs, who attended eight outpatient maternity services in eastern Massachusetts, US between 1999 and 2002.
Out of the 1,255 deliveries, around one in four (22.6%) were by caesarean section, and the remainder (77.4%) were vaginal deliveries.
The study also found those mothers who delivered by c-section weighed more than those delivering vaginally, and the birthweight of their babies also tended to be higher.
Such women also breastfed their babies for a shorter period.
The researchers suggest the weight difference could be explained by the difference in the composition of gut bacteria acquired at birth between the two delivery methods.
Previous research has shown babies born by c-section have higher numbers of Firmicutes bacteria and lower numbers of Bacteroides bacteria in their guts.
It is thought that the gut bacteria could influence the development of obesity by increasing energy extracted from the diet, and by stimulating cells to boost insulin resistance, inflammation, and fat deposits.
Sue Macdonald, Education and Research Manager at the Royal College of Midwives, said the research highlights the need to avoid caesareans that are not medically needed.
“Evidence is building and suggests that unnecessary caesarean sections may have detrimental effects in the short and long term for the woman, and the child,” she said.
“This research adds to that evidence but further research is needed to confirm these findings.
“There is also a need to provide on-going support to women, their babies and families towards improving and addressing weight management, initially through supporting breastfeeding and then through healthy eating.”