The purpose of the present study is to assess the relationship between
early acute otitis media (AOM) and exposure to respiratory pathogens
mediated by siblings and day-care. A prospective cohort of 3,754 Norwe
gian children born in 1992-93 was followed from birth through 12 month
s. One or more episodes of AOM had been experienced by 25% of the chil
dren before age one. Logistic regression analysis showed that siblings
attending day-care is the most important risk factor for early AOM (O
Radj = 1.9 (1.4-2.3)). The total number of children in the day-care se
tting is another determinant for early AOM (ORadj = 2.0 (1.4-2.6) in g
roups of 4 or more other children and ORadj = 1.3 (1.0-1.7) in groups
of 1-3 other children as compared with those who are cared for alone).
Siblings who attend day-care and the number of children in the child'
s own day-care setting are the most important determinants for AOM the
first year of life.