Summary

Background: Feeding neonates with humanized milk formula in maternity hospitals may increase the prevalence of milk allergy in infants. However, prospective studies of the possible allergenic effect of very early soy-based formula feeding are lacking.

Objectives: To assess the prevalence of soy allergy in infants fed soy-based formula in the first 3 days of life.

Methods: The study group included 982 healthy full-term infants born within a 7 month period at a hospital that routinely uses soy-based formula to supplement breastfeeding. In-hospital feeding was recorded and the parents were interviewed once monthly over the next 6 months regarding feeding practices and clinical symptoms suggesting soy allergy in the infant.

Results: Ninety-nine percent of the infants received soy-based formula supplement in hospital, and 33–42% at home. No cases of immediate allergic reaction to soy or soy-induced enterocolitis were reported.

Conclusions: The use of soy-based formula in the early neonatal period does not apparently increase the prevalence of soy allergy in infants followed for the next 6 months.