Objective: To determine whether the frequency of infections during the first 8 years of life varies according to age at initiation and type of group child care (GCC).
Design: Eight-year (1998-2006) prospective cohort study.
Setting: Families with a newborn living in Quebec in 1998.
Participants: A representative sample of families (n = 1238) selected through birth registries.
Main exposure: Home care compared with small or large GCC during the early (ie, before 2½ years old) or late (3½-4½ years old) preschool period.
Main outcome measures: Maternal reports of children's respiratory tract, ear, and gastrointestinal tract infections during the early preschool, late preschool, and early elementary school (5-8 years old) periods.
Results: Compared with children cared for at home, those who started large GCC in the early preschool period had higher rates of respiratory tract infections (incidence rate ratio [IRR], 1.61; 95% confidence interval [CI], 1.27-2.03) and ear infections (IRR, 1.62; 95% CI, 1.19-2.20) during that period but lower rates of respiratory tract infections (IRR, 0.79; 95% CI, 0.66-0.96) and ear infections (IRR, 0.57; 95% CI, 0.37-0.88) during the elementary school years.
Conclusions: Children contract infections around the time they initiate large structured group activities. Participation in large GCC before 2½ years old, although associated with increased infections at that time, seems to protect against infections during the elementary school years. Physicians may reassure parents that infections during the first child care years do not lead to a higher overall burden of infections.