Early childhood development programmes vary in coordination and quality, with inadequate and inequitable access, especially for children younger than 3 years. New estimates, based on proxy measures of stunting and poverty, indicate that 250 million children (43%) younger than 5 years in low-income and middle-income countries are at risk of not reaching their developmental potential. There is therefore an urgent need to increase multisectoral coverage of quality programming that incorporates health, nutrition, security and safety, responsive caregiving, and early learning. Equitable early childhood policies and programmes are crucial for meeting Sustainable Development Goals, and for children to develop the intellectual skills, creativity, and wellbeing required to become healthy and productive adults. In this paper, the first in a three part Series on early childhood development, we examine recent scientific progress and global commitments to early childhood development. Research, programmes, and policies have advanced substantially since 2000, with new neuroscientific evidence linking early adversity and nurturing care with brain development and function throughout the life course.
Introduction
Two Lancet Series on Child Development in Developing Countries (2007 and 2011) spearheaded the review of evidence linking early childhood development with adult health and wellbeing. The finding that 219 million (39%) children younger than 5 years (under-5s) in low-income and middle-income countries (LMICs) are at risk of not reaching their developmental potential, leading to an average deficit of 19·8% in adult annual income,1 attracted global attention.2 These two Series reviewed evidence related to key biological and psychosocial risks; summarised neuroscientific evidence on both adverse and positive experiences affecting early brain development; reviewed effectiveness of programmes and policies to improve early childhood development; provided the estimated costs of not investing in preschools; and concluded that inequities in development begin prior before conception, and that timely interventions reduce inequities and increase productivity (appendix pp 2).3, 4, 5, 6
New evidence supports a life course perspective on childhood development and strengthens the conclusions and recommendations from the earlier Lancet Series, primarily through advances in neuroscience and longitudinal follow-up approaches. Poverty and adverse childhood experiences have long-term physiological and epigenetic effects on brain development and cognition.7, 8, 9 Neural processes, influenced by genetic and epigenetic variation, underlie the attachment and early learning systems, influencing subsequent health and development.10 Longitudinal follow-up studies among children exposed to poverty and other adverse conditions show beneficial effects of interventions on adult wage earning,11, 12 competence (eg, intelligence quotient, educational attainment, and general knowledge),13, 14 health biomarkers,15 reductions in violence, depressive symptoms and social inhibition,14 and growth in the subsequent generation.16, 17 These findings provide strong economic justification for investment in early childhood,18 especially in children younger than 3 years (under-3s).19
In response to the loss of human potential associated with early adversities, leaders from international organisations have issued urgent calls for strategies to ensure that young children reach their developmental potential.2 This Series responds to those calls. Paper 1 proposes a life course perspective and the study of global commitments to early childhood development; Paper 2 examines evidence to implement and sustain effective early childhood development programmes at scale;20 and Paper 3 proposes models and strategies to promote early childhood development at scale.21 This Series focuses on the period from conception up to and including under-5s. Particular attention is given to children under the age of 3, because of the importance associated with the sensitivity and vulnerability of early brain development, the relative lack of attention to early childhood development in general during this period, and the potential for service delivery through the health, nutrition, and social protection sectors.
Key messages
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The proportion of children younger than 5 years in low-income and middle-income countries at risk of not attaining their developmental potential because of extreme poverty and stunting remains high (43%).
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The accumulation of adversities, beginning before conception and continuing throughout prenatal and early life, can disrupt brain development, attachment, and early learning. Developmental delays are evident in the first year, worsen during early childhood, and continue throughout life.
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Despite substantial progress in early childhood development research, programmes, and national policies since 2000, services are of varying quality with uncoordinated and inequitable access, especially for children younger than 3 years.
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Children's early development requires nurturing care—defined as health, nutrition, security and safety, responsive caregiving, and early learning—provided by parent and family interactions, and supported by an environment that enables these interactions.
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Coordination, monitoring, and evaluation are needed across sectors to ensure that high quality early childhood development services are available throughout early childhood and primary school, up to the age of 8 years.
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Action at global, national, and local levels is needed to increase political commitment to and investment in early childhood development.
This first paper has five objectives: (1) to update the estimates of children at risk of not attaining their developmental potential; (2) to present a life course conceptual framework of early childhood development; (3) to assess global commitments and progress in early childhood development since 2000; (4) to examine access to centre-based and home-based early childhood development programmes; and (5) to describe cross-sectoral opportunities to implement early childhood development programmes.
Section snippets
Estimates of children at risk of not attaining developmental potential
Since the 2007 Lancet publication of the number of under-5 children in LMICs at risk for not reaching their developmental potential due to stunting and extreme poverty,1 definitions of stunting and extreme poverty have been updated, with improvements to the source data and estimation methods. As a result, the estimated number of children in LMICs at risk of not reaching their developmental potential, calculated in 2004, was revised from 219 million to 279 million.22 Between 2004 and 2010, the
Life course conceptual framework of early childhood development
Childhood development is a maturational and interactive process, resulting in an ordered progression of perceptual, motor, cognitive, language, socio-emotional, and self-regulation skills.25 Although the developmental process is similar across cultures, progression rates can vary as children acquire culture-specific skills.24 The acquisition of skills and learning in middle childhood, throughout adolescence, and into adulthood builds on foundational capacities established between preconception
Global commitments to early childhood development
We examined changes since 2000 in global commitments to early childhood development using a policy process heuristic72 (figure 2). This heuristic assesses progress in five categories: agenda setting, evaluation, implementation, policy formation, and leadership and partnership.
We used five approaches to collect data related to the heuristic. First, we conducted a 2000–14 literature review on early childhood development risk and protective factors6 to examine changes in the knowledge base (
Home activities
Low-cost activities, such as storytelling, singing, and playing with household objects, expose young children to experiences that promote early development.81 According to Multiple Indicator Cluster Survey data from 2005–15, 48·4% of the nearly 230 000 3 year-olds and 4 year-olds sampled had an adult read to them, and 67·7% had an adult either name or count objects within 3 days before the survey. These figures vary by wealth quintile within countries worldwide, with reading ranging from 62·4%
Opportunities to coordinate early childhood development across sectors
The implementation of early childhood development programmes is often fragmented, particularly for children under 3 years, with confusion between multisector and integrated approaches. Multisector approaches include coordinated services across sectors, ideally with unifying policies.91 Integrated approaches refer to integration across services with shared messages and opportunities for synergy.92 Although there have been multiple calls for integrated services,92 logistical issues remain.59 We
Conclusions
Despite remarkable progress in early childhood development research, programmes, and policies, services for young children are inadequate and inequitably distributed. The burden of children not reaching their developmental potential remains high. The lack of attention to nurturing care as a comprehensive concept is a major concern, especially during the period of rapid brain development and learning, and the formation of caregiver–child attachments that characterises children under 3 years.
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By the time children start primary school, large socioeconomic disparities are evident in their learning and development. Both pre-primary and home environments can play important roles in influencing school readiness and can contribute to disparities in early childhood development, but there is limited evidence on their relative roles in the Middle East and North Africa. This paper examines how pre-primary quality, stimulation at home, and early childhood development vary by socioeconomic status for pre-primary students in Egypt. The results demonstrate substantial socioeconomic inequality in stimulation at home, more so than in pre-primary quality and inputs, although there is variation in the degree of inequality across different dimensions of pre-primary quality. “Double inequality” is observed, where students with less stimulating home environments experience slightly lower quality pre-primary inputs. There are particularly large pre-primary inequities in structural quality (physical environment) and less inequity in process quality (pedagogy). These results suggest that targeted investments in pre-primary education in Egypt are necessary to reduce inequality in school readiness but are likely insufficient to close the socioeconomic status gap in children's development. Investing in interventions to improve vulnerable children's home learning environments, as well as investing in quality pre-primary, is critical to address disparities in children's development.
Given the size of the problem and the scientific evidence that timely intervention can improve long-term outcomes, an important question is how to best scale-up early childhood development (ECD) interventions in low- and middle-income countries (LMICs). A key component of the solution is financing. However, there has been little research on the question of whether cost-sharing models can equitably and sustainably finance ECD programs at scale in LMICs. We built parenting centers in two rural communities of Western China to teach caregivers how to stimulate child development through fun and interactive activities. We used the Becker-Degroot-Marschak (BDM) mechanism to elicit the household willingness-to-pay (WTP) for a one-month pass to the parenting centers. The results of the BDM suggest that a cost-sharing model would not be suitable for China's rural population at least in the short-run. Demand was found to be highly elastic. In addition, we found limited evidence of selection effects. We also found no evidence of sunk-cost effects.
Despite the crucial role of fathers’ parenting activities in early child development and the increasing global attention to fathers’ parenting behaviors, these is a paucity of knowledge regarding paternal parenting in rural China. Using a rich dataset of 1145 infants from rural China, we described the prevalent paternal parenting behaviors in the sample area and explored the correlations between fathers’ parenting behaviors and children’s cognitive outcome and socio-emotional development. To assess children’s cognitive development, we utilized various scales based on their development stages: the Bayley Scales of Infant Development-Third Edition (BSID-III) for ages 6–24 months and the Wechsler Preschool and Primary Scale of Intelligence-Fourth Edition (WPPSI-IV) for ages 52–85 months. Our overall findings revealed positive correlations between paternal behaviors and developmental outcomes of sampled children, including cognitive skills and social-emotional development. Fathers’ parenting behaviors in rural China are insufficient and need to be improved. Specifically, less than a quarter of fathers reported engaging in activities such as telling stories using picture books, singing songs, or playing with toys with their children in the past three days. Based on our findings, we recommend that local government provide additional parenting instructions to heighten fathers’ awareness and participation in parenting activities, especially in rural low-income areas. Additionally, creating more employment opportunities in their hometowns for fathers with young children could substantially benefit these children.
Hundreds of millions of children in low- and middle-income countries are exposed to chronic stressors, such as poverty, poor sanitation and hygiene, and sub-optimal nutrition. These stressors can have physiological consequences for children and may ultimately have detrimental effects on child development. This study explores associations between biological measures of chronic stress in early life and developmental outcomes in a large cohort of young children living in rural Bangladesh.
We assessed physiologic measures of stress in the first two years of life using measures of the hypothalamic-pituitary-adrenal (HPA) axis (salivary cortisol and glucocorticoid receptor gene methylation), the sympathetic-adrenal-medullary (SAM) system (salivary alpha-amylase, heart rate, and blood pressure), and oxidative status (F2-isoprostanes). We assessed child development in the first two years of life with the MacArthur-Bates Communicative Development Inventories (CDI), the WHO gross motor milestones, and the Extended Ages and Stages Questionnaire (EASQ). We compared development outcomes of children at the 75th and 25th percentiles of stress biomarker distributions while adjusting for potential confounders using generalized additive models, which are statistical models where the outcome is predicted by a potentially non-linear function of predictor variables.
We analyzed data from 684 children (49% female) at both 14 and 28 months of age; we included an additional 765 children at 28 months of age. We detected a significant relationship between HPA axis activity and child development, where increased HPA axis activity was associated with poor development outcomes. Specifically, we found that cortisol reactivity (coefficient −0.15, 95% CI (−0.29, −0.01)) and post-stressor levels (coefficient −0.12, 95% CI (−0.24, −0.01)) were associated with CDI comprehension score, post-stressor cortisol was associated with combined EASQ score (coefficient −0.22, 95% CI (−0.41, −0.04), and overall glucocorticoid receptor methylation was associated with CDI expression score (coefficient −0.09, 95% CI (−0.17, −0.01)). We did not detect a significant relationship between SAM activity or oxidative status and child development.
Our observations reveal associations between the physiological evidence of stress in the HPA axis with developmental status in early childhood. These findings add to the existing evidence exploring the developmental consequences of early life stress.
2024, Journal of Economic Behavior and Organization
We show that the development of abstract reasoning and cognitive empathy (theory of mind) is severely hindered when children are deprived of the stimulation of a school environment. We document significantly lower abstract reasoning and cognitive empathy scores in elementary school children who returned from an extended school closure caused by the Covid-19 pandemic relative to proximate pre-pandemic cohorts. This developmental delay has a significant socioeconomic gradient, with underprivileged children experiencing more substantial delays. We also document a significant disruption in the development of socioemotional skills: 0.24 sd lower grit, 0.43 sd lower emotional empathy, 0.06 sd lower epistemic curiosity, and 0.24 sd higher impulsivity. About eight months of school exposure results in a remarkable recovery in abstract reasoning and theory of mind for all socioeconomic groups. However, the measured levels still indicate significant delays relative to the expected developmental trajectories. No notable improvements are observed in socioemotional skills except for curiosity. These findings reveal that the damage school closures inflicted on children goes beyond well-documented academic losses and highlight the crucial role of the school environment in fostering fundamental cognition and socioemotional development in children.
Succinic semialdehyde dehydrogenase deficiency (SSADHD) (OMIM #271980) is a rare autosomal recessive metabolic disorder caused by pathogenic variants of ALDH5A1. Deficiency of SSADH results in accumulation of γ-aminobutyric acid (GABA) and other GABA-related metabolites. The clinical phenotype of SSADHD includes a broad spectrum of non-pathognomonic symptoms such as cognitive disabilities, communication and language deficits, movement disorders, epilepsy, sleep disturbances, attention problems, anxiety, and obsessive-compulsive traits. Current treatment options for SSADHD remain supportive, but there are ongoing attempts to develop targeted genetic therapies. This study aimed to create consensus guidelines for the diagnosis and management of SSADHD. Thirty relevant statements were initially addressed by a systematic literature review, resulting in different evidence levels of strength according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria. The highest level of evidence (level A), based on randomized controlled trials, was unavailable for any of the statements. Based on cohort studies, Level B evidence was available for 12 (40%) of the statements. Thereupon, through a process following the Delphi Method and directed by the Appraisal of Guidelines for Research and Evaluation (AGREE II) criteria, expert opinion was sought, and members of an SSADHD Consensus Group evaluated all the statements. The group consisted of neurologists, epileptologists, neuropsychologists, neurophysiologists, metabolic disease specialists, clinical and biochemical geneticists, and laboratory scientists affiliated with 19 institutions from 11 countries who have clinical experience with SSADHD patients and have studied the disorder. Representatives from parent groups were also included in the Consensus Group. An analysis of the survey's results yielded 25 (83%) strong and 5 (17%) weak agreement strengths. These first-of-their-kind consensus guidelines intend to consolidate and unify the optimal care that can be provided to individuals with SSADHD.