AbstractIntroductionRespiratory infections and wheeze have a considerable impact on the health of young children and consume significant healthcare resources. We aimed to evaluate the effect of environmental factors on respiratory infections and symptoms in early childhood.MethodsEnvironmental risk factors including: daycare attendance; breastfeeding; siblings; damp within the home; environmental tobacco smoke (ETS); child's bedroom flooring; animal exposure; road traffic density around child's home; and solid fuel pollution within home were assessed in children recruited to the GO‐CHILD multicentre prospective birth cohort study. Follow‐up information on respiratory infections (bronchiolitis, pneumonia, otitis media and cold or flu), wheeze and cough symptoms, healthcare utilisation and medication prescription was collected by postal questionnaires at 12 and 24 months. Log binomial and ordered logistic regression models were fitted to the data.ResultsFollow‐up was obtained on 1344 children. Daycare was associated with increased odds of pneumonia (odds ratio [OR] = 2.39, 95% confidence interval [CI]: 1.04−5.49), bronchiolitis (OR = 1.40, 1.02−1.90), otitis media (OR = 1.68, 1.32−2.14) and emergency department attendance for wheeze (RR = 1.81, 1.17−2.80). Breastfeeding beyond 6 months was associated with a reduced odds of bronchiolitis (OR = 0.55, 0.39−0.77) and otitis media (OR = 0.75, 0.59−0.99). Siblings at home was associated with an increased odds of bronchiolitis (OR = 1.65, 1.18−2.32) and risk of reliever inhaler prescription (RR = 1.37, 1.02−1.85). Visible damp was associated with an increased odds of wheeze (OR = 1.85, 1.11−3.19), and risk of reliever inhaler (RR = 1.73, 1.04−2.89) and inhaled corticosteroid prescription (RR = 2.61, 1.03−6.59). ETS exposure was associated with an increased odds of primary care attendance for cough or wheeze (OR = 1.52, 1.11−2.08). Dense traffic around the child's home was associated with an increased odds of bronchiolitis (OR = 1.32, 1.08−2.29).ConclusionEnvironmental factors likely influence the wide variation in infection frequency and symptoms observed in early childhood. Larger population studies are necessary to further inform and guide public health policy to decrease the burden of respiratory infections and wheeze in young children.