Synnve Schjolberg, a specialist in clinical psychology at the Norwegian Institute of Public Health, said preschool children in Norway attend different types of childcare arrangements but most attend kindergarten.
The report is based on questionnaire data from parents of more than 60,000 children ages 18 months, in the period from 2001 to 2009.
Overall, the report shows neither language skills nor psychological function of most children vary with the type of childcare, their age when starting in childcare outside the home, whether they used a combination of childcare arrangements or just one type, or how many hours per week they were in childcare.
"For most children there is no evidence from our findings to suggest that it is harmful to begin in center-based childcare at 12 months," Schjolberg said in a statement. "The small effect sizes of the findings indicate that the differences between children attending childcare at an early age and those starting later have no clinical implications for most children. Neither do the findings suggest that most children who are cared for at home up to 18 months of age are better prepared than children cared for by others in the same period."