Little Evidence That Time in Child Care Causes Externalizing Problems During Early Childhood in Norway


  • The authors acknowledge the Norwegian Mother and Child Cohort Study, which is supported by the Norwegian Ministry of Health, NIH/NIEHS (Grant N01-ES-85433), NIH/NINDS (Grant 1 UO1 NS 047537-01), and the Norwegian Research Council/FUGE (Grant 151918/S10). The authors express their deep appreciation for Stuart Hauser, MD, PhD, a cherished mentor and friend who made this international collaboration possible. Three of the authors (HDZ, ED, and COT) received support from the Norwegian Research Council. The authors acknowledge feedback from Drs. Burchinal and McCartney, and from three anonymous reviewers.


Associations between maternal reports of hours in child care and children's externalizing problems at 18 and 36 months of age were examined in a population-based Norwegian sample (= 75,271). Within a sociopolitical context of homogenously high-quality child care, there was little evidence that high quantity of care causes externalizing problems. Using conventional approaches to handling selection bias and listwise deletion for substantial attrition in this sample, more hours in care predicted higher problem levels, yet with small effect sizes. The finding, however, was not robust to using multiple imputation for missing values. Moreover, when sibling and individual fixed-effects models for handling selection bias were used, no relation between hours and problems was evident.