Bronchiolitis group: Change of associations between salivary morning cortisol at and QoL₂ at two years of age by socioeconomic factors, including age, gender, and the following socioeconomic factors: Mother’s education, father’s education, mother’s income, father’s income, ethnicity of father and of mother (Caucasian or not) and secondhand smoke exposure at two years of age.

The socioeconomic factors have been eliminated by Hosmer’s stepdown procedure, finally retaining factors with p<0.05. Age and gender have been retained in the models.