by Claudia Boyd-Barrett posted in Pregnancy

For some time now, we've been hearing that birth by C-section could increase babies' risk of becoming overweight. But a large, new study involving pairs of siblings suggests that may not be the case.
Several studies have suggested a link between childhood obesity and birth by C-section. But those studies were often small and didn't take into account other factors that could influence children's weight such as cultural differences, race and ethnicity, the mom's weight, or whether their family was poor.
In the most recent study, published in JAMA Pediatrics, scientists sought to rule out the influence of family circumstances on obesity risk by comparing children born to the same mom but delivered differently. Using long-term clinical data collected on thousands of children in eastern Massachusetts, the researchers identified 2,000 sibling pairs in which one child was delivered vaginally, and one by C-section. Among children in the same family, the mode of birth had no impact on whether or not the children were overweight by age 5, the researchers found. They concluded that reducing C-section frequency would likely not have a big impact on childhood obesity rates.

The study had some limitations. All of the families had health insurance, so the findings might not apply to moms and children without good access to medical care. Also, the researchers did not have information about the moms' pre-pregnancy weight, which could have influ...