A recent study done by researchers at Boston Children's Hospital seems to indicate that children born by cesarean section are twice as likely to become obese by toddlerhood as their peers born vaginally. Given the childhood obesity epidemic, a statistic like that causes one to pause and think. The study notes that the rate of c-section has gone up dramatically in the past 30 years. It also notes the fact that the rate of childhood obesity has increased at a rapid rate. The study's authors note that new information out about the microbes living on and in our body are beginning to be studied for their effect on human metabolism and nutrition, among many other things. The c-section study's author then theorizes that a change in microbial growth in the gastrointestinal tract related to type of birth delivery may be causing the large rate of obesity seen in the toddlers after c-section.
The "Spurious Relationship"
When conducting research, one error that can be made is finding a "spurious relationship." This type of error happens when researchers see coinciding events and determine that they are related. For example, one notices that ice cream sales go up in summer. One also notes that fires increase in summer. One therefore determines that ice cream sales cause fires. Clearly other factors are in play. The same can be said of the c-section and obesity relationship. If you take a look at the study, the findings aren't as clear, or as large, as the researchers claim.
The Demographics of Childhood Obesity
One troubling fact noted in the study was that the c-section population did not have an increased risk for overweight status, only obesity. This result lends itself to the question of whether the results were skewed for some reason. Further, the population for this study was generally Caucasian, affluent, and well-educated women. When one looks at the childhood obesity epidemic, the most affected population is generally poor children born to parents with limited education. Finally, the most jarring fact is one that the researchers address only briefly. When adjusting for the body mass index of mothers, the results remain, but are decreased. A well-designed study would adjust for multiple factors, especially the body mass index of mothers, before pronouncing a worrisome conclusion.
The Birth of a New Myth?
All this is not to say that there may not be some link between c-section and change in gut microbiome, or an eventual link to obesity. The science simply is not there yet. Any woman facing a c-section due to a medical complication in her pregnancy should not be influenced by the theorized risk of increased incidence of obesity. Obesity in childhood is related to so many factors that taking one out in isolation is almost useless. These types of studies are helpful in structuring future research, showing researchers where they may look next in the quest for understanding the human body and current health trends.
Unfortunately, too often, they are related to the public as gospel truth. This is how nutrition myths get started.
Jennifer Webb, MS, RD, CNSC is a practicing dietitian and freelance writer based out of Southern California. She has been practicing medical nutrition therapy for the past five years. Prior to her career in nutrition, she received a degree in early childhood development. She has combined her two passions, nutrition and family, into a career educating people about the impact food can have on health across the lifespan. She is currently a dietitian at a top children's hospital and runs a private practice. Her private practice specializes in family nutrition therapy, a technique that focuses on changing family habits to lead them to lifelong healthy lifestyles. Contact Jennifer at firstname.lastname@example.org.