Last Updated: 2003-09-03 11:20:43 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Some infants who are delivered by cesarean section may have an increased risk of developing food allergies, according to a new report published in the August issue of the Journal of Allergy and Clinical Immunology.

Investigators have identified a relationship between cesarean section delivery and subsequent food allergy in children of mothers with allergies.

Cesarean delivery might delay the growth of normal intestinal flora--bacteria that normally line the intestine--in the newborn infant, Dr. Merete Eggesbo, of the Norwegian Institute of Public Health in Oslo, and colleagues note. One theory is that delays or abnormalities in the growth of these bacteria may increase the risk of allergic disease.

To further investigate, the researchers obtained data on mode of delivery, maternal or infant use of antibiotics, and potential confounding factors in a population of 2803 children. The main outcome measures were the parent's opinions of their child's reaction to egg, fish, or nuts. The child's reaction to egg at 2.5 years of age was also objectively confirmed by laboratory tests.

For children with allergic mothers, the researchers found that cesarean section was associated with a sevenfold increased rate of parental reports of reactions to egg, fish, or nuts in children. The risk of confirmed egg allergy was increased by fourfold in these children.

For children without allergic mothers, the association between cesarean section and the risk of food allergy was weak and not significant.

There was no association between maternal or infant antibiotic use and an increased risk of food allergy.

These results "lend circumstantial support to the importance of microbiologic stimuli in early life," Eggesbo and colleagues conclude. They suggest that this might be another factor to consider when mode of delivery is discussed with pregnant women.