Variable | Source | Type | Coding |
---|---|---|---|
Primary outcome | |||
GP amoxicillin prescribing | Electronic primary care records | Binary | ≥1 prescription each year: yes/no |
Secondary outcome | |||
GP consultation for URTI | Electronic primary care records | Binary | ≥1 consultation each year: yes/no |
GP consultation for LRTI | Electronic primary care records | Binary | ≥1 consultation each year: yes/no |
Exposure | |||
Sex of infant | Maternity records | Binary | Male |
Female | |||
Delivery mode | Maternity records | Binary | Vaginal |
Caesarean | |||
Quarter of birth | Maternity records | Categorical | January–March |
April–June | |||
July–September | |||
October–December | |||
Gestational age | Maternity records | Binary | <39 weeks |
≥39 weeks | |||
Congenital anomalies | Congenital anomaly register at Bradford Royal Infirmary | Binary | 0 congenital anomalies |
≥1 congenital anomaly | |||
Ethnic background | BiB baseline questionnaire | Categorical | White British |
Pakistani, UK-born | |||
Pakistan, non-UK born | |||
Other | |||
Socioeconomic status | BiB baseline questionnaire | Categorical | Least deprived and most educated |
Employed not materially deprived | |||
Employed with no access to money | |||
On benefits but coping | |||
Most deprived | |||
Maternal smoking during pregnancy | BiB baseline questionnaire | Binary | Smoked during pregnancy: yes/no |
Breastfeeding duration | ALL-IN 12-month questionnaire | Categorical | <1 month |
1–<6 months | |||
≥6 months | |||
Childcare | ALL-IN 12-month and 24-month questionnaires | Binary | Child in formal childcare: yes/no |
Number of people in household | ALL-IN 12-month and 24-month questionnaires | Binary | Child in overcrowded (6 people) dwelling: yes/no |
Household mould/damp | ALL-IN 12-month and 24-month questionnaires | Binary | Child in dwelling with visible mould/damp: yes/no |
Gas cooking | ALL-IN 12-month and 24-month questionnaires | Categorical | Gas cooking only |
Gas and electric cooking | |||
Electric cooking only | |||
Quartile of PM2.5 in relation to Bradford level | Department for Environment, Food and | Categorical | 1st/2nd quartile |
Rural Affairs linked with LSOA from BiB | 3rd quartile | ||
baseline questionnaire and ALL-IN | 4th quartile | ||
12-month questionnaire |
ALL-IN = allergy and infection. BiB = Born in Bradford. LRTI = lower respiratory tract infection. LSOA = lower super output area. PM2.5 = particulate matter ≤2.5 µm. URTI = upper respiratory tract infection.