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Health Equity: Comprehensive, Center-Based Programs for Children of Low-Income Families to Foster Early Childhood Development (Archived)


What the Task Force Found

About The Systematic Review

The Task Force finding is based on evidence from a systematic review of 16 studies (search period 1965-2000). The review was conducted on behalf of the Task Force by a team of specialists in systematic review methods, and in research, practice, and policy related to promoting health equity.

Summary of Results

Sixteen studies qualified for the review.

  • The review assessed four different categories of outcomes: cognitive, social, health, and family.
  • Nine studies measured academic achievement through use of standardized academic achievement assessments, such as the Woodcock-Johnson or California Achievement Test.
    • Six studies demonstrated increases in academic achievement for students enrolled in early childhood development programs.
    • One study reported a negative effect.
    • Two studies provided no data to calculate effect sizes.
    • Academic achievement scores increased by a median of 0.35 standard deviations.
  • School readiness: median effect size of 0.38 standard deviations (3 studies)
  • IQ: median effect size of 0.43 standard deviations (6 studies)
    • Although these results are positive, the influence of this gain in IQ on longer-term health and social outcomes is not known.
  • Student retention: program participants were 13% less likely to be retained (“held back“) in grade level (5 studies)
  • Placement in special education programs: program participants were 14% less likely to be placed in special education programs (5 studies)



Evidence Gaps

Each Community Preventive Services Task Force (Task Force) review identifies critical evidence gaps—areas where information is lacking. Evidence gaps can exist whether or not a recommendation is made. In cases when the Task Force finds insufficient evidence to determine whether an intervention strategy works, evidence gaps encourage researchers and program evaluators to conduct more effectiveness studies. When the Task Force recommends an intervention, evidence gaps highlight missing information that would help users determine if the intervention could meet their particular needs. For example, evidence may be needed to determine where the intervention will work, with which populations, how much it will cost to implement, whether it will provide adequate return on investment, or how users should structure or deliver the intervention to ensure effectiveness. Finally, evidence may be missing for outcomes different from those on which the Task Force recommendation is based.

Identified Evidence Gaps

The search for suitable studies evaluating the effectiveness of early childhood development programs on factors other than intellectual functioning revealed significant gaps in research. Although the body of published research is large, relatively few studies assess program impact on subsequent health, well-being, and social success. A 1997 Government Accounting Office report on Head Start found the body of research inadequate for drawing conclusions about its national impact due to a limited focus on short-term cognitive measures. The report also noted important methodological and design weaknesses, such as non-comparability of comparison groups and lack of the large representative samples necessary to produce results that can be generalized to the national program.

The lack of scientific evidence about social outcomes, child health screening outcomes, and family outcomes is noteworthy, especially because these outcomes relate specifically to program objectives and mandated components in Head Start programs. In terms of social outcomes, a lack of standardized measures and the challenges of implementing longitudinal follow-up may have contributed to the paucity of evidence in this important domain. New research funded by the U.S. Department of Health and Human Services, including the National Head Start Impact Study and the Quality Research Consortium II, holds promise of providing more information on social and emotional development, communications skills, physical well-being, and the family effects of Head Start programs.

It is encouraging that, in addition to the high level of national attention generated by the results of the Perry Preschool program, other promising longitudinal studies with strong research designs examining the impact of early childhood development programs have recently been published and have garnered interdisciplinary interest. (These studies were not included in our systematic review because they did not compare participation in comprehensive ECD programs with nonparticipation). One such study looked at the long-term (15-year) effects of the Chicago Child-Parent Center Program, compared with other early childhood intervention programs, on educational achievement and juvenile arrest among low-income African-American children in Chicago. Another longitudinal study examined the relation of the quality of preschool child care to children’s development during their preschool years, and subsequently as they moved into a formal elementary education system. The need still exists, though, for additional studies of strong experimental or quasi-experimental research design using appropriate social, health, and family outcome measures to generate sufficient scientific evidence of the effects of early childhood development programs in these domains.

Research also needs to be expanded to closely examine core characteristics of effective and efficient early childhood development programs: teacher-student ratio, curriculum structure, optimum intensity (i.e., hours per day, months per year), qualifications of program staff, and levels of parental involvement.

Finally, the complex interactions of biology, individual and family characteristics, and the social and physical environments posited by the Community Guide’s social environment and health logic model underscore the need for additional research, consistent with an ecological perspective. Although there is strong evidence from early childhood intervention studies that improvements in cognitive function can translate into early school success, understanding the full impact of childhood social environments on later life experiences will require an interdisciplinary, multilevel research approach. The Office of Behavioral and Social Science Research of the National Institutes of Health has called for integrated sociobehavioral and biomedical research, and an example of this kind of undertaking can be found in a collaborative study authorized by the Children’s Health Act of 2000. This act authorizes the National Institute for Child Health and Development to collaborate with the Centers for Disease Control and Prevention, the National Institute for Environmental Health Science, and the Environmental Protection Agency to conduct a national longitudinal study of environmental influences (including physical, chemical, biological, and psychosocial) on children’s health and development. This interdisciplinary research will be critical to generating needed information for policy decisions on funding and coordination of early childhood development programs within the context of interrelated community services. Current levels of federal and state funding for early childhood development programs are not adequate to support accessible, quality services for the number of at-risk children who could potentially benefit from participation.

Study Characteristics

  • The early childhood development programs reviewed were “center-based” (i.e., in a public school or child development center), providing an alternative physical and social environment to the home.
  • Some reviewed programs included a home visitation component.
  • Reviewed programs operated full or half days, 9 to 12 months a year.