Increased Risk of Adult Obesity Linked to C-Sections

Summary
Obesity and the number of Cesarean section deliveries have increased simultaneously over the last few years. This study from Brazil tries to find a connection. The study was started in 1978 with 2,057 case studies, when data was collected about the kind of delivery, health and habits of the mother and the weight of the infant. It was followed up from 2002 to 2004, when the body mass index (BMI) of the subjects was recorded together with their health, habits and economic status. Those born by Cesarean delivery seem to have a higher chance of becoming obese in adulthood.

Introduction
Increasing obesity in the population has led to investigation of its causes. The rates of Cesarean deliveries have also steadily risen. “A possible mechanism that might be hypothesized to link the increasing rates of obesity and Cesarean delivery could be related to environmental factors.” Some microorganisms live in the human gut; changes in their composition may affect the way humans digest food and store energy. An infant born by Cesarean section is not exposed to the microorganisms in the mother’s birth canal. This delays the emergence of some microbes in the infant’s gut. It is observed that these microbes are lesser in number in Cesarean-delivered babies as well as in obese people. The study hypothesizes that Cesarean-delivered babies are at a higher risk to develop obesity.

Methods
* Data was collected for babies born in a hospital in Brazil from 1978 to 1979. Of these, 2,057 were randomly studied from 2002 to 2004 for analysis.
* The individuals were requested to answer a lifestyle questionnaire about their health as well as social and economic status.
* A physical checkup was done for each, and standard methods were used for statistical analysis.
* “Economic, social, and maternal health care data were obtained from a standardized questionnaire completed by the mothers soon after delivery, and demographic information was collected from official records.”

Results
* The Cesarean delivery rate was much higher in educated women than in less-educated ones.
* The average BMI of those born by Cesarean delivery was about 25, while it was about 24 for those born by vaginal delivery.
* After reaching adulthood, 15.2 percent of Cesarean-born people showed obesity, while 10.4 percent of vaginally born people showed obesity. Obesity was more in less educated, lower income groups.
* People born by Cesarean section are at 58 percent higher risk for developing obesity after reaching adulthood than those born by vaginal delivery.

Shortcomings/Next steps
Breastfeeding of a newborn infant may introduce certain necessary microorganisms into the infant’s body, probably lowering the risk of obesity during adulthood. This study has not considered data regarding breastfeeding. In addition, the connection between Cesarean and maternal weight has been not considered. Further studies regarding the premature breaking of water and the time the labor lasted are required.

Conclusion
The chances of a Cesarean baby developing obesity in adulthood are significant, according to this study. The reasons for obesity could be mild inflammation early in life caused by Cesarean delivery. The microorganisms colonizing the intestines affect a person’s energy storage and digestion. Cesarean babies are usually exposed early on to certain microorganisms in the mother’s vagina. One hypothesis suggests that if this does not occur, it may result in immunological differences. Breastfeeding also introduces these microorganisms into the infant’s body. However, it is not clear if initiation or duration of breastfeeding is affected by Cesarean delivery. There may also be a higher risk of type 1 diabetes, adding to the chances of obesity.

For More Information:
Cesarean Delivery Is Associated with an Increased Risk of Obesity in Adulthood in a Brazilian Birth Cohort Study
Publication Journal: American Journal of Clinical Nutrition, April 2011
By Helena AS Goldani; Heloisa Bettiol; Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil

*FYI Living Lab Reports Are Summaries of the Original Research.



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