Baseline questionnaire data
| Family and demographic | Family history of allergic disease (allergy, eczema, hay fever, asthma), maternal BCG vaccination, parent education, parent country of birth, ethnicity. |
| Household environment | Size, composition, smoking, pets, region (postal code). |
| Maternal prenatal | Age, weight, height, prior pregnancies, vaccinations, smoking, antibiotics, vitamin D, probiotics other medications or supplements. |
| Birth | Mode of delivery*, birth site*, plurality*, birth complications, gestational age, weight, sex, antibiotics or other medications during labour. |
*Required for stratification prior to randomisation.