Cord blood 25-hydroxyvitamin D levels are associated with aeroallergen sensitization in children from Tucson, Arizona

Background The association between vitamin D status at birth and childhood allergic outcomes is uncertain. The desert climate of Tucson offers a unique setting for studying the health effects of higher exposure to vitamin D. Objective To assess the relationship between cord blood 25-hydroxyvitamin D (25[OH]D) levels and allergic outcomes through age 5 years. Methods Cord blood 25(OH)D levels were measured in 219 participants in the Tucson Infant Immune Study, a population-based birth cohort. Plasma total IgE and specific IgE levels to 6 aeroallergens were measured at 1, 2, 3, and 5 years. Skin prick test (SPT) positivity (wheal diameter ≥3 mm) and physician-diagnosed active allergic rhinitis and asthma were assessed at age 5 years. Longitudinal models were used to assess the relationship between 25(OH)D and IgE levels. Logistic regression models were used to assess the relationship of 25(OH)D level with SPT positivity, allergic rhinitis, and asthma. Results The median cord blood 25(OH)D level was 64 nmol/L (interquartile range, 49-81 nmol/L). Relative to the reference group (50-74.9 nmol/L), both low (