SAN DIEGO – Results from a large randomized trial indicate that greater degrees of breast-feeding exclusivity do not lead to lower levels of allergic sensitization, Dr. Bruce D. Mazer reported in a poster presentation at the annual meeting of the American Academy of Allergy, Asthma, and Immunology.
In fact, the study provides some indication that breast-feeding may actually increase sensitization to several common allergens, according to Dr. Mazer of McGill University, Montreal, and his coinvestigators. “There are a lot of good reasons to breast-feed, but prevention of allergic sensitization is not one of them,” Dr. Mazer said in an interview.
The study involved a secondary analysis of the Promotion of Breast-Feeding Intervention Trial (PROBIT) in which 17,046 healthy newborns and their mothers seen at 31 maternity hospitals in the Republic of Belarus were randomized (hospital by hospital) to receive either standard instruction on infant nutrition or enrollment in a program modeled on the Baby-Friendly Hospital Initiative of the World Health Organization and United Nations Children's Fund, which emphasizes health-care worker assistance with initiating and maintaining lactation and breast-feeding.
Among the original findings of that study were that infants of women randomized to the program were far more likely to receive their nutrition exclusively by breast-feeding at follow-up at 3 months and 6 months of age than were infants of women receiving standard instruction.
When these children reached the age of 6.5 years, 13,889 mother-child pairs were identified and approached for further study, which included skin-prick testing and an assessment of allergic symptoms and diagnoses based on the International Study of Asthma and Allergy in Childhood (ISAAC) questionnaire. More than 99% of the mother-child pairs completed the questionnaire, and 11,145 of the children (80%) underwent skin-prick testing.
There were no significant differences between children who had been assigned to the program and those in the control group in their answers to any of the ISAAC questions. In addition, after adjustment for which maternity hospital they had been seen in, there were no significant differences in the percentages of children who tested positive to any of five common allergens.
The investigators noted that six of the maternity hospitals had unusually high rates of positive skin-prick tests. When data from those suspect sites were eliminated from the analysis, the investigators found that children in the program were significantly more likely to have positive skin-prick tests to dust mites, cats, birch pollen, and Alternaria, but not to mixed northern grasses.
“Our results underline the importance of seeking other explanations for the recent epidemic of allergy and asthma, and of investigating other potential etiologic factors to develop and test new preventive interventions,” the investigators concluded.