C-section delivery may double the risk of subsequent childhood obesity; say researchers who believe differences in gut bacteria acquired at birth may be key. The research appears in the journal Archives of Disease in Childhood.
The authors of the study have based their findings on 1,255 mother and child pairs who attended outpatient maternity services in Massachusetts between 1999 and 2002. The babies were measured and weighed at birth, at six months, and then at the age of three, when the child's skinfold thickness (a measure of body fat) was also assessed.
Out of the 1,255 deliveries, 23 percent were by caesarean section, and the remaining 77 percent were vaginal deliveries.
The researchers noted that the moms who delivered by c-section tended to weigh more than those delivering vaginally, and the birthweight for gestational age of their babies also tended to be higher. These moms also breastfed their babies for a shorter period.
But irrespective of birth weight, and after taking account of maternal weight and several other influential factors, a caesarean section delivery was associated with a doubling in the odds of obesity by the time the child was 3 years old. Specifically, 16 percent of children delivered via c-section were obese by the age of 3 compared with 8 percent of those born vaginally.
The researchers speculate that one possible explanation for their findings is the difference in the composition of gut bacteria acquired at birth between the two delivery methods. They highlight previous research showing that children born by c-section have higher numbers of Firmicutes bacteria and lower numbers of Bacteroides bacteria in their guts. These two groups make up the bulk of gut flora. Other research has also suggested that obese people have higher levels of Firmicutes bacteria.
It may be that gut bacteria influence the development of obesity by increasing energy extracted from the diet, and by stimulating cells to boost insulin resistance, inflammation, and fat deposits, say the researchers. "An association between caesarean birth and increased risk of childhood obesity would provide an important rationale to avoid non-medically indicated caesarean section," they conclude.
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Source: British Medical Journal