A structured telephone questionnaire is administered to the mother/parent when their child is 4 and again at 6 years. Trained interviewers employed in the Vanderbilt Survey Research Shared Resource use a web-based computer system to conduct structured telephone interviews, which capture detailed information on asthma and atopy diagnoses and symptoms, extensive environmental exposure history, physical activity, and comorbidities. Asthma, AR and atopic dermatitis outcomes are determined using the ISAAC questionnaire. For children with report of asthma and/or asthma symptoms in the previous 12 months, the Asthma Therapy Assessment Questionnaire is administered, and information on asthma medications, and asthma-related health-care visits are sought. 12, 13 Biospecimen collection and laboratory analyses Table 3 outlines the details of cohort biospecimen collection, repository and testing, which includes infant nasopharyngeal, urine, blood and nasal epithelial cell sample collection, and maternal prick skin testing and blood samples.