Protective and risk factors for allergic diseases in high-risk children at the ages of two and five years.

Background: Environmental and lifestyle factors such as breast-feeding and pets seem to affect atopic disease prevalence. We identified risk factors for allergic diseases.

Methods: We prospectively followed until the age of 5 years a cohort of 1,223 children born into allergic families, who participated in a randomized placebo-controlled trial of probiotics as preventive against allergic disease.