Introduction
Scientific findings from diverse disciplines are in agreement that critical elements of lifelong health, well-being and productivity are shaped during the first 2–3 years of life,1 beginning with parental health and well-being.2 The experiences and exposures of young children during this time-bound period of neuroplasticity shape the development of both biological and psychological structures and functions across the life course.
Adversities during pregnancy and early childhood, due to undernutrition, stress, poverty, violence, chronic illnesses and exposure to toxins, among others, can disrupt brain development, with consequences that endure throughout life and into future generations.3 4 Children whose early development is compromised have fewer personal and social skills and less capacity to benefit from schooling. These deficits limit their work opportunities and earnings as adults.5 A corollary of early susceptibility to adversity includes responsiveness to opportunities during these early years. As a result, interventions during the first 3 years of life are more effective and less costly than later efforts to compensate for early adversities and to promote human development.6
It is estimated that, in 2010, at least 249 million (43%) children under the age of 5 years in low-income and middle-income countries (LMICs) were at risk of poor early childhood development (ECD) as a consequence of being stunted or living in extreme poverty.7 This loss of potential is costly for individuals and societies. The average percentage loss of adult income per year is estimated at 26%, increasing the likelihood of persistent poverty for these children, families and societies.5 Assuming 125 million children are born each year with a global average of poor infant growth,8 the estimated annual global income loss is US$177 billion.9 These impacts have serious consequences on economic growth. Recent World Bank estimates suggest that the average country’s per capital gross domestic product would be 7% higher than it is now had stunting been eliminated when today’s workers were children.10 At the global level, human capital accounts for as much as two-thirds of the wealth differences between countries. ECD is the foundation of human capital.11
Supported by a growing body of evidence and increasing global interest in this field, ECD is included in the 2015 United Nations Sustainable Development Goals (SDGs). Target 4.2 is ‘improved access to quality early childhood development, care and pre-primary education’. Progress towards achieving this target is measured by indicator 4.2.1, ‘the proportion of children under 5 years of age who are developmentally on track in health, learning and psychosocial well-being, by sex’. ECD is closely linked to other SDGs as well, for example, eradicate poverty (1), end hunger and improve nutrition (2), ensure healthy lives (3), achieve gender equality (5), reduce inequality in and among countries (10), and promote peaceful societies (16), and it is implied in several more.5
The United Nations Global Strategy for Women’s, Children’s and Adolescents’ Health, 2016–2030 synthesises the 17 SDGs in three strategies: survive, thrive and transform. Survive refers to sustained and increased reductions in preventable deaths of women, newborns, children and adolescents, as well as stillbirths; thrive refers to children receiving the nurturing care necessary to reach their developmental potential; and transform refers to comprehensive changes in policies, programmes and services for women, children and adolescents to achieve their potential.12
ECD has also become an important component of other global agendas, including Scaling Up Nutrition, the Global Partnership for Education, the Global Financing Facility for Every Woman Every Child, the Every Woman Every Child movement, the work plans of the WHO, Unicef and the World Bank Group, the G20,13 international funding agencies, and philanthropic foundations.7
These multifaceted findings have generated political momentum to improve ECD as a critical phase in the life course, making it urgent to develop measurement tools and indicators to monitor progress globally and in countries. Advances in measurement are needed to support efforts to motivate and track political and financial commitments, and to monitor implementation and impact. This means that we must be able to determine how many and which children are thriving, and on track in health, learning and psychosocial well-being.
Measurement of children’s progress in childhood is acknowledged to be challenging because development is by nature dynamic and children have varying individual trajectories. Well-validated instruments of individual development are complex and require extensive training and expertise. These challenges are amplified in efforts to make measurements across populations of children. Taking these limitations into account, we review progress in three areas of measurement that are contributing data to the current political momentum for ECD and efforts to monitor implementation and impact. Progress is being made to construct a feasible country-comparable measure of young children’s development that could be incorporated into national surveys, to improve proxies of population levels of young children at risk of poor early development, and to generate country profiles of determinants, drivers and coverage for early childhood development and services, using currently available data.