First-Year Antibiotics Exposure in Relation to Childhood Asthma, Allergies, and Airway Illnesses.

: Associations of early antibiotics exposures with childhood asthma, allergies, and airway illnesses are debated. : We aimed to investigate associations of first-year antibiotics exposure with childhood asthma, allergies, and airway illnesses. : A cross-sectional study was conducted among preschoolers in Shanghai, China during 2011-2012. A questionnaire regarding household environment and lifestyles and childhood health outcomes was reported by the child's parents. : In total, 13,335 questionnaires (response rate: 85.3%) were analyzed and 3049 (24.1%) children had first-year antibiotics exposure. In the multivariate logistic regression analyses, first-year antibiotics exposure had significant associations with the higher odds of lifetime-ever pneumonia (adjusted OR, 95% CI: 2.15, 1.95-2.37), croup (1.46, 1.24-1.73), wheeze (1.44, 1.30-1.60), asthma (1.38, 1.19-1.61), food allergy (1.29, 1.13-1.46), and allergic rhinitis (1.23, 1.07-1.41), and as well as current (one year before the survey) common cold (≥3 times) (1.38, 1.25-1.52), dry cough (1.27, 1.13-1.42), atopic dermatitis (1.25, 1.09-1.43), wheeze (1.23, 1.10-1.38), and rhinitis symptoms (1.15, 1.04-1.26). These associations were different in children with different individual characteristics (age, sex, family history of atopy, and district) and other early exposures (breastfeeding, home decoration, pet-keeping, and environmental tobacco smoke). : Our results indicate that first-year antibiotics exposure could be a strong risk factor for childhood pneumonia, asthma, allergies, and their related symptoms. The individual characteristics and other early exposures may modify effects of early antibiotic exposure on childhood allergies and airway illnesses.