Zachrisson, H. D., Dearing, E., Lekhal, R. and Toppelberg, C. O. (2013), Little Evidence That Time in Child Care Causes Externalizing Problems During Early Childhood in Norway. Child Development, 84: 1152-1170. doi: 10.1111/cdev.12040
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 (n = 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.
The impact of time spent in early child care on social-emotional development is a contentious issue among social scientists and the public alike. Indeed, there remains a lack of empirical consensus on the topic. One review of the cumulative work in the U.S. concludes that, among child care predictors of socio-emotional problems, quantity of care is the strongest and most consistent, with more hours predicting more problems (Jacob, 2009). Yet, more recently, researchers have found this prediction to be sporadically evident, but not robust, when using conservative controls for potential selection bias (McCartney et al., 2010).
The scientific and public debate has, to date, relied heavily on child care studies in the United States and on one longitudinal study in particular - the NICHD Study of Early Child Care and Youth Development (NICHD SECCYD). For this reason, sociopolitical context must be considered; quantity findings in U.S. samples must be interpreted with attention to the lack of regulatory standards at the federal level for child care quality and professional development (Love et al., 2003), and a relatively early average age of entry into non-parental care due to the relatively short average length of parental leave (UNICEF Innocenti Research Center, 2008). A greater scientific focus on child care in countries with publicly subsidized and regulated child care is the next logical step for the field. In the present study, we examined associations between hours in child care and externalizing behavior problems in a large, population-based longitudinal Norwegian study.