Abstract
OBJECTIVE: We aimed to assess increased birth weight or birth length in relation to allergic diseases at 4 years of age, taking body mass index (BMI) at age 4 as a covariate in the adjustment. METHODS: The parents of a large prospective birth cohort answered questionnaires on environmental factors and allergic symptoms when their children were 2 months and 1, 2 and 4 years old. Perinatal data on weight and length at birth were received from the child care health centres. The children were clinically examined at 4 years of age and height and weight recorded. Blood was drawn for analysis of specific IgE antibodies to common inhalant allergens. Risk associations between birth anthropometric measures and wheeze, allergic diseases or sensitisation were estimated in multivariate logistic regression analyses (n = 2869). RESULTS: There were no clear overall associations between birth weight and allergic diseases at 4 years of age. Birth length > or =90th percentile was inversely associated with any wheeze at age 4 (adjusted OR 0.64, 95% CI 0.44 to 0.92) but was significantly associated only with late-onset wheeze (adjusted OR 0.40, 95% CI 0.21 to 0.77). No such associations were seen for persistent or transient wheeze, eczema, rhinitis or allergic sensitisation. Transient wheeze during the first 2 years of age tended to be associated with increased BMI at age 4. CONCLUSION: Increased birth weight was not associated with wheeze or allergic disease. Increased birth length may play a protective role in late-onset wheeze in early childhood.