Abstract: We included in the review one trial, involving 120 families and 143 children. Risk of bias was high because of contamination between groups, as 63% of control group participants accessed day care services separate from those offered within the intervention. No evidence suggested that centre-based day care, rather than no treatment (care at home), improved or worsened children's cognitive ability (Griffiths Mental Development Scale, standardised mean difference (SMD) 0.34, 95% confidence interval (CI) -0.01 to 0.69, 127 participants, 1 study, very low-quality evidence) or psychosocial development (parental report of abnormal development, risk ratio (RR) 1.21, 95% CI 0.25 to 5.78, 137 participants, 1 study, very low-quality evidence). No other measures of child intellectual or psychosocial development were reported in the included study. Moreover, no evidence indicated that centre-based day care, rather than no treatment (care at home), improved or worsened employment of parents, as measured by the number of mothers in full-time or part-time employment (RR 1.12, 95% CI 0.85 to 1.48, 114 participants, 1 study, very low-quality evidence) and maternal hours per week in paid employment (SMD 0.20, 95% -0.15 to 0.55, 127 participants, 1 study, very low-quality evidence) or household income above £200 per week (RR 0.86, 95% CI 0.57 to 1.29, 113 participants, 1 study, very low-quality evidence). This study did not report on long-term outcomes for children (high-school completion or income). This review includes one trial that provides inconclusive evidence as regards the effects of centre-based day care for children younger than five years of age and their families in high-income countries. Robust guidance for parents, policymakers and other stakeholders on the effects of day care cannot currently be offered on the basis of evidence from randomised controlled trials. Some trials included co-interventions that are unlikely to be found in normal day care centres. Effectiveness studies of centre-based day care without these co-interventions are few, and the need for such studies is significant. Comparisons might include home visits or alternative day care arrangements that provide special attention to children from low-income families while exploring possible mechanisms of effect.

Plain-language summary: We included studies that assessed the effects of centre-based day care for children younger than five years of age in high-income countries. To isolate the effects of day care, we excluded interventions that involved medical, psychological or non–child-focused co-interventions. Electronic searches identified 34,890 citations that were screened for inclusion in the review. Only one study (120 families, 143 children), based in London, England, matched all inclusion criteria and was included in the review. Evidence is current to April 2014. Currently very limited evidence is available on the effects of centre-based day care on the cognitive and psychosocial development of children, parental employment or household income, or on long-term outcomes for children. Only one randomised controlled trial (RCT) was included in this review. In addition, a large proportion of families in the non-intervention group secured day care services for themselves. The quality of the evidence included in this review is very low, so the results must be interpreted with caution. Although RCTs do not allow conclusive judgements as regards the role of centre-based day care in the development of children and the economic situation of parents, this does not imply that these services are not important in high-income countries. The need for effectiveness studies of centre-based day care without co-interventions is significant. This review is one of a pair of reviews; researchers and practitioners may find evidence from the low- and middle-income country review to be informative also (Brown 2014).