OBJECTIVE: To investigate the relationship between socioeconomic factors, maternal characteristics, breastfeeding, and hospitalization for bronchiolitis in the post-neonatal period. METHODS: A nested case-control study with a cohort of 5,304 children born in the city of Pelotas, Brazil, was conducted. The cohort study consisted of four sub-studies with their own methods and logistics. Mothers were interviewed using a standard questionnaire during in-hospital and home visits. Cases were defined as any child aged 28 to 364 days who had been hospitalized for […]