Throughout the world, there has been widespread recognition that children’s development is shaped by the cultural context and interactions that begin prenatally and extend throughout childhood.1,2  Children raised in stable and nurturing settings that provide adequate nutrition, responsive caregiving, protection from adversities, and opportunities for learning, along with health and educational services, have the best chance of reaching their full developmental potential.3,4  Nurturing interactions begin with families and extend to community programs and services, including childcare providers, and to policies that shape the macrosocial environment. Children’s early competencies can prepare them to achieve increasingly complex competencies throughout childhood and adolescence, and to become healthy, caring, and productive adults, assuming responsibilities for their family, community, and society. With declines in child mortality5  and fertility over the past 30 years,6  resulting in smaller family sizes, along with increases in early childcare7  and parents’ interest in their young children’s learning opportunities,8  it is not surprising that The World Health Organization and other international organizations regard investments in children as an essential strategy to achieving the United National Sustainable Development Goals.1,9,10 

Poverty and environmental deprivation disrupt children’s early brain development during periods of neural plasticity and sensitivity to environmental interactions, leading to long-term negative consequences on children’s health and development.11  The effects of poverty on the developing brain are mediated by caregiving behavior and stressful experiences, illustrating the powerful potential of responsive caregiving.12,13 

In the United States, between 2017 and 2020, 17% of children under 18 years of age (12.6 million children) lived in families with incomes below the poverty line ($26 246 for 2 adults and 2 children).14  Throughout the world, hundreds of millions of children experience poverty and adverse experiences in their communities or households that can disrupt their developmental progress, preventing them from reaching their developmental potential.15  With unrealized human development, children’s ability to escape poverty and build fruitful careers and satisfying lives as adults can be jeopardized. Poverty combined with caregiver stress can undermine children’s exposure to nurturing and developmentally enhancing interactions and opportunities. Globally, it is estimated that over 250 million children under age 5 years are at risk for not meeting their developmental potential.3,16 

The American Academy of Pediatrics (AAP) is committed to the “optimal physical, mental, and social health and well-being for all infants, children, adolescents, and young adults.”17  AAP’s Council on Early Childhood supports the health and wellbeing of young children; high-quality community-based programs, including childcare, preschool, and parenting programs; and cross-sectoral collaboration to promote community-based early childhood systems. These commitments are backed by both functional and neuroscientific evidence from early child development programs. Research programs, such as the Infant Health and Development Program, an intervention trial among low birth weight, premature infants, show stronger cognitive effects at age 3 years among young children from lower versus higher-income families.18  Based on population projections, income gaps in IQ at age 3 years could be eliminated by programs that are universal or reach children at greatest need.19  Government programs, such as Head Start,20  and programs from nonprofit organizations, such as the Nurse Family Partnership and Parents as Teachers, show positive and sustained effects on children’s cognitive and socio-emotional development and school readiness, particularly among children with few resources.21,22  Building from a strong research base, these programs have been implemented across the country, often with community-based partnerships committed to supporting families and young children.

Early childhood development programs have also been developed and implemented in low- and middle-income countries (LMIC). The Jamaica Program developed by Dr. Sally Grantham McGregor and colleagues at the University of the West Indies in the 1970s is a pioneering home visiting program with demonstrated benefits that extend throughout childhood and adolescence, resulting in better employment and higher wages in adulthood.23,24  The Jamaica Program has been translated to “Reach Up Early Childhood Parenting Programme” (https://www.reachupandlearn.com/), known as “Reach Up,” and implemented in at least 16 countries, some at scale. Consistent with the principles of nurturing care,3  Reach Up emphasizes a stable environment that provides protection from threats and opportunities for learning through emotionally supportive and responsive relationships. These experiences have generated insights and lessons on how to effectively implement caregiving intervention programs at scale.

Findings from Reach Up,24  Care for Child Development, developed by the World Health Organization and UNICEF,25  and other home visiting programs implemented among infants and young children in low-resource communities demonstrate the powerful impact of early intervention on children’s cognitive and socio-emotional development.26  Guided by bioecological theory and the recognition that children’s development is enhanced with nurturant and responsive caregivers,27,28  early childhood development programs strengthen the capacity of parents and childcare providers to give young children the nurturing care needed to overcome early adversities and reach their developmental potential.7  Longitudinal studies show that the benefits of early intervention can be maintained into adulthood with positive impacts on adult psychological and economic functioning.24,29 

This supplement originated as a tribute to Professor Sally Grantham-McGregor for her innovative work and commitment to global early childhood development, including the “Order of the British Empire” award for lifetime achievements. The authors of this paper formed a Working Group to organize a supplement dedicated to promoting global early childhood development. We invited over 50 established authors from multiple institutions in high-, middle- and low-income countries to submit concept notes that addressed the implementation of caregiving programs for infants and young children in LMICs. We reviewed 29 concept notes; scored them based on 5 criteria relative to global caregiving interventions (significance, innovation, authors, quality, and potential interest to readers); and invited 20 authors to submit papers or commentaries.

We received and reviewed 16 papers and commentaries and invited 14 authors to prepare revised manuscripts for submission. The supplement relies on principles of equity and implementation science to extend beyond impact evaluations and examine topics relevant to scaling intervention programs to reach the children and families in LMICs at greatest need. The papers address topics related to program quality, including children in conflict and other extremely difficult settings, integrating early intervention with other services, delivering services remotely, and partnering with government agencies, among others.

The initial commentary is written by Professor Heckman, a Nobel laureate in economics who demonstrated the economic benefits of investing in early childhood development.30  His commentary highlights the central role of the family in building successful pathways for young children. The first paper in the supplement is a meta-analysis of 18 studies across 8 countries that implemented the Reach Up program. Jervis et al found benefits on children’s development and home stimulation across 2 delivery strategies (home visits and small groups), implemented at varying levels of scale.31  This analysis highlights how Reach Up has been successfully implemented across multiple settings and among diverse populations, even as a national program. In the second paper, Hossain et al examined the effects of early childhood intervention among children in Bangladesh after 6 years and found sustained effects of cognitive development among children without a history of anemia.32  The anemic group did not experience benefits either immediately following the intervention or at the 6-year follow-up, suggesting that specialized interventions are necessary for children with specific conditions, such as anemia and disabilities. These findings add to the evidence on the sustainability of early intervention, as well as the harmful effects of anemia. The coronavirus disease 2019 pandemic disrupted many early intervention programs. Smith et al evaluated the development, adaptation, implementation, and impact of a remote version of Reach Up implemented through phone, text, and instant messages among caregivers of young children recruited from health centers in Brazil and Jamaica who met risk criteria.33  Through a mixed methods design, they documented the positive effects of remote delivery of the intervention on caregiving practices.

Although there have been multiple calls for integrated interventions,10  few have been implemented. Tofail et al implemented a group-delivered intervention in health facilities in Bangladesh that addressed childhood development, along with maternal mental health.34  Their findings of beneficial effects on multiple domains of children’s development and improvements in mothers’ depressive symptoms and caregiving illustrate the merits of group-delivery of integrated interventions in health facilities. In an innovative design, Meghir et al studied the timing and duration of interventions by comparing children in India randomized to receive interventions delivered before age 3 and/or following age 3.35  Interventions among both age categories benefited children’s IQ and school readiness. The finding that children receiving interventions at both time periods did not experience differential benefits requires additional investigation. The Reach Up program has been implemented among approximately 1500 children in an impoverished region of Western China.36  Zhou et al found that the intervention was successfully implemented at scale, with effect sizes that were comparable to those found among the original Jamaica Program. They note the benefits of starting early and report on program costs.

Although the importance of program quality has been well established,37  there has been limited attention to strategies to advance quality. Bernal et al developed quality enhancement to an existing parenting program in rural Colombia and found benefits to childhood development and to caregiving practices, particularly maternal engagement, when quality was high.38  Their observational measure of quality has the potential to promote and maintain intervention quality at scale. In 2019, over 71 million children under age 5 had spent their entire lives in crisis and conflict zones. Based on their experiences of implementing adapted versions of Reach Up in crisis and conflict areas of Bangladesh, Syria, and Venezuela, Wilton et al documented the importance of cultural adaptation of interventions from a holistic perspective of children and caregivers, the inclusion of safety and linkages to complementary services, and incorporating blended models and costing analyses.39 

Exposure to violence early in life can disrupt children’s brain development, increasing their risk for socio-emotional problems.40  Two papers in the supplement addressed violence prevention. Jensen et al examined associations between intimate partner violence and harsh child discipline in Rwanda.41  They implemented an intervention that reduced harsh discipline by increasing father engagement and parenting warmth among female caregivers, illustrating that violence reduction can be effectively integrated into early childhood development programs to reduce harsh discipline and intimate partner violence. Baker-Henningham et al used implementation science principles in the design, implementation, and scaling of 2 violence-prevention caregiver-training programs for preschoolers in Jamaica: a teacher-training program and a caregiving program.42 

The final paper in the supplement, by King et al, describes a protocol for a cluster randomized trial to evaluate an integrated, multisector, multiplatform intervention to promote childhood development.43  The intervention targets caregiving behaviors in the home and community, and is delivered in partnership with the Royal Government of Cambodia, illustrating the engagement of local governmental agencies. Recognizing the extension of caregiving from the home to community-based settings, such as childcare, is critical with the global increases in women of child-bearing age participating in the work force.7  The supplement concludes with 2 commentaries. Lombardi et al address the unmet needs of childcare for young children throughout the world and recommend public commitment to childcare, with enhanced infrastructure, innovation, and research.44  In the final commentary, Professors Grantham-McGregor and Walker extend their experiences with the Jamaica Program and Reach Up to discuss strategies to implement caregiving and early intervention programs at scale. In addition to the theoretical and programmatic aspects, they address the need for sustainability and leadership in the field of child development, including training and research that is led by researchers and principal investigators living and working in LMICs.45 

In summary, the supplement illustrates that early childhood development programs have been advanced and rigorously investigated throughout the world, improving the lives of thousands of young children and offering the potential for designing programs at scale to overcome the effects of poverty and deprivation on children’s development. Similar to programs in the United States, Reach Up and other global intervention programs began as individually oriented home visiting services, recognizing the critical roles of families in nurturing their children’s development. They have expanded and have successfully been delivered using diverse methodologies – including groups, in diverse settings, including health centers, crisis and conflict areas, and remote delivery, consistent with the AAP’s commitment of providing high-quality community-based programs for children. A primary strength of this collection is the inclusion of 79 authors, many of whom are directly involved with research and service within LMICs. A primary limitation is that we may have missed excellent papers by not doing a general call.

Future steps in scaling childhood development programs will require attention to the principles of implementation science and the cultural context of communities,46,47  including the commitment to reach children and families at the greatest need; workforce development; accountability; strategies to promote program quality, adaptability, and equity; and finally financial investment, fiscal responsibility, and sustainability. Early childhood development programs have the potential to transform the lives of hundreds of millions of young children, thereby increasing the human capital of countries and promoting the attainment of the United Nations’ Sustainable Development Goals.

We thank the New Venture Fund and the Jacobs Foundation for the support of the supplement; the support of the RTI Fellows Program at RTI International to Maureen Black; the contributions of Ana Katrina (Anika) Aquino, M.A. who assisted with the reviews of the manuscripts and the preparation of the manuscripts for submission; the contributions of Joshua Jeong, PhD who assisted with the reviews of the manuscripts; the support of the World Health Organization, UNICEF, the World Bank Group, the Inter-American Development Bank, and other organizations that have supported research into the development of young children throughout the world.

Dr Black was part of the Working Group for the supplement, conceptualized and designed the supplement, reviewed the paper included in the supplement, and drafted the introductory manuscript. Drs Walker, Attanasio, Rubio-Codina, Meghir, Hamadani, Fernald, Kowalski, and Grantham-McGregor were part of the Working Group for the supplement, conceptualized and designed the supplement, reviewed the papers included in the supplement, and reviewed and revised the introductory manuscript; and all authors approved the final introductory manuscript as submitted and agree to be accountable for all aspects of the work.

This paper and supplement present the authors’ views and not those of the institutions they represent, including the Inter-American Development Bank, its board of directors, or the countries they represent.

FUNDING: Funding for the supplement was provided by the New Venture Fund to the University of Maryland School of Medicine and the Jacobs Foundation to Yale University.

CONFLICT OF INTEREST DISCLOSURES: The authors have indicated they have no conflicts of interest relevant to this article to disclose.

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