German researchers found babies born via C-section were twice as likely to be sensitive to common foods, such as cows' milk, at 12 months of age as babies born vaginally. C-section babies were also more likely to have diarrhea during their first year of life.
Researchers say the findings agree with previous research that has demonstrated the importance of bacteria in the gut in the development of a healthy immune system. By bypassing the vaginal birth canal, researchers say that caesarean sections alter or delay normal bacterial development in the baby's gut.
The results of the study appear in the November issue of the Archives of Disease in Childhood.
C-Section May Raise Food Allergy Risks
In the study, researchers looked at 865 healthy, full-term babies whose parents had a history of allergies and were part of the German Infant Nutritional Intervention Study. The babies were all exclusively breastfed during the first four months and had follow-up visits at 1, 4, 8, and 12 months of age.
Blood samples taken at 12 months checked for antibodies to common food allergens (allergy-causing substances) including eggs, cows' milk proteins, and soy protein. The parents also kept weekly diaries on their children's health and feeding for the first six months.
Overall, 147 (17%) of the babies were born by C-section. Caesarean delivery was four times more likely among mothers who had already had a C-section for a previous birth.
But babies born by C-section were 46% more likely to have diarrhea up to age 12 months than vaginally delivered babies.
In addition, C-section babies were also twice as likely to be sensitive to cows' milk and any of the other five food allergens tested at age 12 months.
Researchers suggest that babies delivered via the vaginal canal acquire the mother's vaginal, intestinal, and other bacteria, which may help protect them and promote a healthy immune system. But babies born via C-section acquire bacteria from the hospital environment that may increase the risk of food allergies and other problems.