[Risk factors associated with hospitalization for bronchiolitis in the post-neonatal period].

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 bronchiolitis. RESULTS Among 5,304 cohort children, 113 (2.1%) were hospitalized for bronchiolitis. The hierarchical multivariate analysis performed using logistic regression showed the following results: family income and gestational age were inversely associated with the risk of hospitalization for bronchiolitis. Breastfeeding showed to have a protective effect; children who were breastfed for less than one month had 7 times less risk for being hospitalized for acute bronchiolitis in the first three months of life. The risk for hospitalization for bronchiolitis is 57% higher in those exposed to maternal smoking than in those non-exposed. CONCLUSIONS Hospitalization for acute bronchiolitis is inversely associated with family income, gestational age and duration of breastfeeding and positively associated with maternal smoking. There was not an association with either parity or maternal history of asthma.