The new analysis, published in the United States journal JAMA Pediatrics, included 16 years’ worth of data from more than 22,000 young adults in the Growing Up Today Study, in which participants answered survey questions every year or two years from 1996 to 2012. A total of 16,882 children aged 9 to 14 years responded to the baseline questionnaire, and an additional 10,923 children aged 9 to 14 enrolled in 2004. The mothers of all of these children are also enrolled in our ongoing Nurses’ Health Study II which, by linking the datasets, can provide rich, detailed information on maternal characteristics and pregnancy-related information.
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Explaining this, Chavarro stated: “That’s because, in the case of siblings, numerous factors that could potentially be playing a role in obesity risk, including genetics, would be largely the same for each sibling, except for the type of delivery”.
As important as cesareans are, they are not without risks, Chavarro noted. That was not the case.
A definitive biological cause is yet to be identified to explain this correlation, so until the link can be confirmed, we need to wait and see what further evidence reveals.
C-section births within families, where one sibling is born naturally and another through C-section, were also looked into, and the results were even more surprising, with 64 per cent of the births likely to become obese when they’re older compared to a sibling born by vaginal birth.
Babies born by caesarean section are more likely to be obese as adults, according to a study that suggests the way we are born could have a lasting impact on health.
RG: What other factors did you adjust for? After they took into account factors like the body mass index of mothers before they got pregnant, the magnitude of the risk dropped to 15 percent but remained large enough to be statistically significant. Among these children, almost 5,000 were delivered by cesarean section.
For the study, Chavarro and his Harvard colleagues collected data on more than 22,000 children born to more than 15,000 women. Women who had cesarean delivery had a higher BMI before pregnancy and were more likely to have gestational diabetes, preeclampsia and pregnancy-induced high blood pressure, the study reports.
“This initial difference in mode of delivery leads to changes in the type of bacteria living in children’s guts”, she said.
“Children born via C-section harbour less diverse gut bacteria and these patterns of less diversity have been linked to increased capacity for energy harvest by the gut microbiota”, one of the researchers, Audrey Gaskins, told Hannah Devlin at The Guardian.
RG: Is this something doctors and parents should consider when deciding whether a cesarean birth is the right option? . Otherwise, the risk for their babies to be obese doubles.
“These findings suggest that this association may be a true adverse outcome of cesarean delivery that clinicians and patients should weigh when considering cesarean birth in the absence of a clear medical or obstetric indication.”
RG: What are the next steps for this research?
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“We expected that after controlling for these other risk factors in our analysis, the association between cesarean birth and childhood obesity would completely disappear”. Thus, whether differences in offspring microbiota are sustained long-term still remains to be evaluated.
