2.2 Questionnaires
At baseline and follow-up, questionnaires were completed by the parents/guardians, while children older than 13 years, completed questionnaires themselves (in addition to questionnaires completed by a parent/guardian). At baseline, different versions of the questionnaire covered predefined age brackets (Supplementary Table 1) . The version that participants received was dependent on the participants age at time of the questionnaire (ageQ). Presence of eczema, asthma, and hay fever within each age bracket was reported at baseline. Presence of FA was reported at follow-up.