(RxWiki News) Both the rate of obesity and the rate of elective C-sections have been increasing in the U.S. Though no evidence exists to say one causes another, they may be linked.
A recent study has found that children born via cesarean section were about twice as likely to be obese by the time they were toddlers than babies who were born vaginally.
"Don't choose to have a C-section unless medically necessary."
Susanna Huh, of the Department of Pediatrics at Harvard Medical School and the Division of Gastroenterology and Nutrition at Children's Hospital Boston, led the three-year study.
Huh and her team studied 1,255 pairs of mothers and their children in eastern Massachusetts between 1999 and 2002. The women enrolled in the study before their 22nd week of pregnancy and were tracked for three years after their baby's birth.
The researchers weighed and measured the babies at birth, at 6 months old and at 3 years old. When the children were 3, their body fat was also measured by their skinfold thickness.
Approximately a quarter of the deliveries (23 percent) were C-sections, and the researchers found that the children born to these women were about twice as likely to be obese by age 3.
While only 7.5 percent of the babies born vaginally were obese at age 3, 16 percent of the children born by C-section were obese toddlers.
The mothers who delivered by C-section tended to be heavier than those who had vaginal deliveries, and their babies at birth were also larger, on average, than other babies born at the same number of weeks of pregnancy.
After taking into account the babies' larger initial birthweight and the body mass index of the mothers, however, the double-risk of obesity remained. Even among the 3-year-olds who were not obese, they tended to have larger BMI and skinfold thickness measurements than the toddlers who had been born vaginally.
The researchers theorize that one possible reason for the increased risk of obesity among C-section-born children is that they have different combinations of bacteria in their guts than the vaginally born children do.
They developed this theory based on previous research they cite that shows a different ratio of the two primary bacteria groups in the digestive systems of children born via C-section compared to those born vaginally.
The bacteria that the C-section-born children have more of, called Firmicutes bacteria, also appears to occur in higher levels in obese people, according to past research, the authors wrote.
If the gut bacteria plays a part in how much energy the body can pull from the food a person eats and play a part in the person's insulin resistance, then it could influence their risk of obesity.
"An association between caesarean birth and increased risk of childhood obesity would provide an important rationale to avoid non-medically indicated caesarean section," the authors wrote.
The study appeared online May 23 in the Archives of Disease in Childhood. The research was funded by grants from the National Institute of Health. The authors declared no conflicts of interest.