Abstract: Children’s experiences during early childhood are critical for their cognitive and socio-emotional development, two key dimensions of human capital. However, children from low income backgrounds often grow up lacking stimulation and basic investments, leading to developmental deficits that are difficult, if not impossible, to reverse later in life without intervention. The existence of these deficits are a key driver of inequality and contribute to the intergenerational transmission of poverty. In this paper, we discuss the framework used in economics to model parental investments and early childhood development and use it as an organizing tool to review some of the empirical evidence on early childhood research. We then present results from various important early childhoods interventions with emphasis on developing countries. Bringing these elements together we draw conclusions on what we have learned and provide some directions for future research.

Abstract: In this paper we use high quality data from two developing countries, Ethiopia and Peru, to estimate the production functions of human capital from age 1 to age 15. We characterize the nature of persistence and dynamic complementarities between two components of human capital: health and cognition. We also explore the implications of different functional form assumptions for the production functions. We find that more able and higher income parents invest more, particularly at younger ages when investments have the greatest impacts. These differences in investments by parental income lead to large gaps in inequality by age 8 that persist through age 15.

Abstract: This paper uses the data on child development collected around the evaluation of a nursery program to estimate the details of the process of human development. We model development as made of three latent factors, reflecting health, cognitive and socio-emotional skills. We observe children from age 1 to age 7. We assume that, at each age, these factors interact among themselves and with a variety of other inputs to determine the level of development at following ages. Relative to other studies, the richness of the data we use allows us to: (i) let the dynamics be rich and flexible; (ii) let each factors play a role in the production of any other factor; (iii) estimate age-specific functional forms; (iv) treated parental investment as an endogenous input. We find that the dynamics of the process can be richer than usually assumed, which has important implications for the degree of persistence of different inputs in time. Persistence also changes with age. This has important implications for the targeting of investment and interventions, and the identification of windows of opportunities. The endogeneity of investment is also important.

Abstract: We study the importance of maternal subjective beliefs about the technology of skill formation in determining parental investments on child development. We describe our framework in three steps. First, we discuss the construction of the survey instrument we used to elicit maternal subjective beliefs. Second, we show how to convert the answers to the survey instrument into estimates of maternal subjective beliefs. Finally, we correlate maternal subjective beliefs with maternal investments of child development. We apply our framework to a unique dataset collected as part of an 18-month-long parenting stimulation program in Colombia, whose target population were low-income households with children aged 12 to 24 months at baseline and lasted 18 months. In this program, home visitors paid weekly visits to randomly chosen households to improve mother-child interactions and other maternal behaviors that foster the development of children’s cognitive and non-cognitive skills. We show that the vast majority of mothers believe that the technology of skill formation follows a Cobb-Douglas parameterization, but there is significant heterogeneity in coefficients of investments across mothers. In particular, mothers hold low subjective expectations, which means that mothers underestimate the returns to their investments. We also find that maternal subjective beliefs predict investments, but that the program did not affect maternal subjective beliefs.

Abstract: Global access to preschool has increased dramatically yet preschool quality is often poor. We use a randomized controlled trial to evaluate two approaches to improving the quality of Colombian preschools. We find that the first, which was rolled out nationwide and provides additional resources for materials and new staff, did not benefit children’s development and, unintentionally, led teachers to reduce their involvement in classroom activities. The second approach additionally trains teachers to improve their pedagogical methods. We find this addition offset the negative effects on teacher behavior, improved the quality of teaching and raised children’s cognition, language and school readiness.

Abstract: Early childhood development is becoming the focus of policy worldwide. However, the evidence on the effectiveness of scalable models is scant, particularly when it comes to infants in developing countries. In this paper, we describe and evaluate with a cluster-Randomized Controlled Trial an intervention designed to improve the quality of child stimulation within the context of an existing parenting program in Colombia, known as FAMI. The intervention improved children’s development by 0.16 of a standard deviation (SD) and children’s nutritional status, as reflected in a reduction of 5.8 percentage points of children whose height-for-age is below -1 SD.

Abstract: We examine the channels through which a randomized early childhood intervention in Colombia led to significant gains in cognitive and socio-emotional skills among a sample of disadvantaged children aged 12 to 24 months at baseline. We estimate the determinants of parents’ material and time investments in these children and evaluate the impact of the treatment on such investments. We then estimate the production functions for cognitive and socio-emotional skills. The effects of the program can be explained by increases in parental investments, emphasizing the importance of parenting interventions at an early age.

Abstract: Colombia’s national early childhood strategy launched in 2011 aimed at improving the quality of childcare services offered to socio-economically vulnerable children, and included the possibility that children and their childcare providers could transfer from non-parental family daycare units to large childcare centers in urban areas. This study seeks to understand whether the offer to transfer and the actual transfer from one program to the other had an impact on child cognitive and socioemotional development, and nutrition, using a cluster-randomized control trial with a sample of 2767 children between the ages of 6 and 60 months located in 14 cities in Colombia. The results indicate a negative effect of this initiative on cognitive development, a positive effect on nutrition, and no statistically significant effect of the intervention on socioemotional development. We also explored the extent to which these impacts might be explained by differences in the quality of both services during the transition, and report that quality indicators are low in both programs but are significantly worse in centers compared to community nurseries

Abstract: Poor early childhood development (ECD) in low- and middle-income countries is a major concern. There are calls to universalise access to ECD interventions through integrating them into existing government services but little evidence on the medium- or long-term effects of such scalable models. We previously showed that a psychosocial stimulation (PS) intervention integrated into a cash transfer programme improved Colombian children’s cognition, receptive language, and home stimulation. In this follow-up study, we assessed the medium-term impacts of the intervention, 2 years after it ended, on children’s cognition, language, school readiness, executive function, and behaviour.

Abstract: The relationship between early adversity and numerous negative outcomes across the lifespan is evident in a wide range of societies and cultures (e.g., Pakulak, Stevens, & Neville, 2018). Among the most affected neural systems are those supporting attention, self-regulation, and stress regulation. As such, these systems represent targets for neurobiologically informed interventions addressing early adversity. In prior work with monolingual native English-speaking families, we showed that a two-generation intervention targeting these systems in families improves outcomes across multiple domains including child brain function for selective attention (for detail, see Neville et al., 2013). Here, we discuss the translation and cultural adaptation (CA) of this intervention in local and international contexts, which required systematic consideration of cultural differences that could affect program acceptability. First, we conducted a translation and CA of our program to serve Latino families in the United States using the Cultural Adaptation Process (CAP), a model that works closely with stakeholders in a systematic, iterative process. Second, to implement the adapted program in Medellín, Colombia, we conducted a subsequent adaptation for Colombian culture using the same CAP. Our experience underscores the importance of consideration of cultural differences and a systematic approach to adaptation before assessing the efficacy of neurobiologically informed interventions in different cultural contexts.

Abstract: Research has previously shown a gap of near 0.5 of a standard deviation (SD) in cognition and language development between the top and bottom household wealth quartile in children aged 6–42 months in a large representative sample of low- and middle-income families in Bogota, using the Bayley Scales of Infant and Toddler Development. The gaps in fine motor and socio-emotional development were about half that size. Developmental deficits increased with age. The current study explored the associations amongst child development, household socio-economic status (SES), and a set of potential mediating variables—parental characteristics, child biomedical factors, and the quality of the home environment—in this sample. We ran mediation tests to quantify the contribution of these variables to the SES gap, and explored the role of age as a moderator. Parental education, particularly maternal education, and the quality of the home environment mediated the SES gap in all outcomes examined. Height-for-age mediated a small amount of the deficit in language scales only. More educated mothers provided better home stimulation than less educated mothers and the home environment partly mediated the effect of maternal education. These results suggested that in interventions aimed at promoting child development, those focusing on the quality of the home environment should be effective.

Abstract: In Colombia’s bottom socio-economic strata, 46.6% of children under two are anaemic. A prevalence of above 20% falls within the WHO guidelines for daily supplementation with multiple micronutrient powder (MNP). To evaluate the effect of daily MNP supplementation on anaemia amongst Colombian children aged 12–24 months we ran a cluster RCT (n=1440). In previous work, we found the intervention had no impact on haemoglobin or anaemia in this population. In this current paper, we investigate this null result and find it cannot be explained by an underpowered study design, inaccurate measurements, low adoption of and compliance with the intervention, or crowding out through dietary substitution. We conclude that our intervention was ineffective at reducing rates of childhood anaemia because MNP itself was inefficacious in our population, rather than poor implementation of or adherence to the planned intervention. Further analysis of our data and secondary data suggests that the evolution with age of childhood anaemia in Colombia, and its causes, appear different from those in settings where MNP has been effective. Firstly, rates of anaemia peak at much earlier ages and then fall rapidly. Secondly, anaemia that remains after the first year of life is relatively, and increasingly as children get older, unrelated to iron deficiency. We suggest that factors during gestation, birth, breastfeeding and early weaning may be important in explaining very high rates of anaemia in early infancy. However, the adverse effects of these factors appear to be largely mitigated by the introduction of solid foods that often include meat. This renders population wide MNP supplementation, provided after a diet of solid foods has become established, an ineffective instrument with which to target Colombia’s childhood anaemia problem.

Abstract: In low- and middle-income countries (LIMCs), measuring early childhood development (ECD) with standard tests in large scale surveys and evaluations of interventions is difficult and expensive. Multi-dimensional screeners and single-domain tests (‘short tests’) are frequently used as alternatives. However, their validity in these circumstances is unknown. We examined the feasibility, reliability, and concurrent validity of three multi-dimensional screeners (Ages and Stages Questionnaires (ASQ-3), Denver Developmental Screening Test (Denver-II), Battelle Developmental Inventory screener (BDI-2)) and two single-domain tests (MacArthur-Bates Short-Forms (SFI and SFII), WHO Motor Milestones (WHO-Motor)) in 1,311 children 6–42 months in Bogota, Colombia. The scores were compared with those on the Bayley Scales of Infant and Toddler Development (Bayley-III), taken as the ‘gold standard’. The Bayley-III was given at a center by psychologists; whereas the short tests were administered in the home by interviewers, as in a survey setting. Findings indicated good internal validity of all short tests except the ASQ-3. The BDI-2 took long to administer and was expensive, while the single-domain tests were quickest and cheapest and the Denver-II and ASQ-3 were intermediate. Concurrent validity of the multi-dimensional tests’ cognitive, language, and fine motor scales with the corresponding Bayley-III scale was low below 19 months. However, it increased with age, becoming moderate-to-high over 30 months. In contrast, gross motor scales’ concurrence was high under 19 months and then decreased. Of the single-domain tests, the WHO-Motor had high validity with gross motor under 16 months, and the SFI and SFII expressive scales showed moderate correlations with language under 30 months. Overall, the Denver-II was the most feasible and valid multi-dimensional test and the ASQ-3 performed poorly under 31 months. By domain, gross motor development had the highest concurrence below 19 months, and language above. Predictive validity investigation is needed to further guide the choice of instruments for large scale studies.

Abstract: We study the socioeconomic gradient of child development on a sample of low- and middle-income children aged 6–42 months in Bogota using the Bayley Scales of Infant and Toddler Development. We find an average difference of 0.53, 0.42, and 0.49 standard deviations (SD) in cognition, receptive, and expressive language respectively, between children in the top and bottom quartile of the wealth distribution. These gaps increase substantially to 0.81 SD (cognition), 0.76 SD (receptive language), and 0.68 SD (expressive language) for children aged 31–42 months. These robust findings can inform the design and targeting of interventions promoting early childhood development.

Abstract:
Objective: To assess the effectiveness of an integrated early child development intervention, combining stimulation and micronutrient supplementation and delivered on a large scale in Colombia, for children’s development, growth, and hemoglobin levels.
Design: Cluster randomized controlled trial, using a 2×2 factorial design, with municipalities assigned to one of four groups: psychosocial stimulation, micronutrient supplementation, combined intervention, or control.
Setting: 96 municipalities in Colombia, located across eight of its 32 departments.
Participants: 1420 children aged 12-24 months and their primary carers.
Intervention: Psychosocial stimulation (weekly home visits with play demonstrations), micronutrient sprinkles given daily, and both combined. All delivered by female community leaders for 18 months.
Main outcome measures: Cognitive, receptive and expressive language, and fine and gross motor scores on the Bayley scales of infant development-III; height, weight, and hemoglobin levels measured at the baseline and end of intervention.
Results: Stimulation improved cognitive scores (adjusted for age, sex, testers, and baseline levels of outcomes) by 0.26 of a standard deviation (P=0.002). Stimulation also increased receptive language by 0.22 of a standard deviation (P=0.032). Micronutrient supplementation had no significant effect on any outcome and there was no interaction between the interventions. No intervention affected height, weight, or hemoglobin levels.
Conclusions: Using the infrastructure of a national welfare program we implemented the integrated early child development intervention on a large scale and showed its potential for improving children’s cognitive development. We found no effect of supplementation on developmental or health outcomes. Moreover, supplementation did not interact with stimulation. The implementation model for delivering stimulation suggests that it may serve as a promising blueprint for future policy on early childhood development.
Trial registration: Current Controlled trials ISRCTN18991160.

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Abstract: Social connections are fundamental to human wellbeing. This paper examines the social networks of young married women in rural Odisha, India. This is a group for whom highly-gendered norms around marriage, mobility and work are likely to shape opportunities to form and maintain meaningful ties with other women. We track the social networks of 2,170 mothers over four years, and find a high degree of isolation. Wealthier women and women from more-advantaged castes and tribes have smaller social networks than their less-advantaged peers. These gradients are primarily driven by the fact that more-advantaged women are less likely to know other women within the same socioeconomic group than are less-advantaged women. There exists strong homophily by socioeconomic status (SES) that is symmetric across socioeconomic groups. Mediation analysis shows that SES differences in social isolation are strongly associated with ownership of toilets and labor force participation. Further research should investigate the formation and role of female networks.

Abstract:
Objectives: Poor early childhood development in low- and middle-income countries is a major public health problem. Efficacy trials have shown the potential of early childhood development interventions but scaling up is costly and challenging. Guidance on effective interventions’ delivery is needed. In an open-label cluster-randomized control trial, we compared the effectiveness of weekly home visits and weekly mother-child group sessions. Both included nutritional education, whose effectiveness was tested separately.
Methods: In Odisha, India, 192 villages were randomly assigned to control, nutritional education, nutritional education and home visiting, or nutritional education and group sessions. Mothers with children aged 7 to 16 months were enrolled (n = 1449). Trained local women ran the two-year interventions, which comprised demonstrations and interactions and targeted improved play and nutrition. Primary outcomes, measured at baseline, midline (12 months), and endline (24 months), were child cognition, language, motor development, growth and morbidity.
Results: Home visiting and group sessions had similar positive average (intention-to-treat) impacts on cognition (home visiting: 0.324 SD, 95% confidence interval [CI]: 0.152 to 0.496, P = .001; group sessions: 0.281 SD, 95% CI: 0.100 to 0.463, P = .007) and language (home visiting: 0.239 SD, 95% CI: 0.072 to 0.407, P = .009; group sessions: 0.302 SD, 95% CI: 0.136 to 0.468, P = .001). Most benefits occurred in the first year. Nutrition-education had no benefit. There were no consistent effects on any other primary outcomes.
Conclusions: Group sessions cost $38 per child per year and were as effective on average as home visiting, which cost $135, implying an increase by a factor of 3.5 in the returns to investment with group sessions, offering a more scalable model. Impacts materialize in the first year, having important design implications.

Abstract: We estimate production functions for cognition and health for children aged 1–12 in India, based on the Young Lives Survey. India has over 70 million children aged 0–5 who are at risk of developmental deficits. The inputs into the production functions include parental background, prior child cognition and health, and child investments, which are taken as endogenous. Estimation is based on a nonlinear factor model, based on multiple measurements for both inputs and child outcomes. Our results show an important effect of early health on child cognitive development, which then becomes persistent. Parental investments affect cognitive development at all ages, but more so for younger children. Investments also have an impact on health at early ages only.

Abstract:
Background: An estimated 63.4 million Indian children under 5 years are at risk of poor development. Home visits that use a structured curriculum to help caregivers enhance the quality of the home stimulation environment improve developmental outcomes. However, achieving effectiveness in poor urban contexts through scalable models remains challenging.
Methods: Using a cluster randomised controlled trial, we evaluated a psychosocial stimulation intervention, comprising weekly home visits for 18 months, in urban slums of Cuttack, Odisha, India. The intervention is complementary to existing early childhood services in India and was run and managed through a local branch of a national NGO. The study ran from August 2013 to July 2015. We enrolled 421 children aged 10–20 months from 54 slums. Slums were randomised to intervention or control. Primary outcomes were children’s cognitive, receptive language, expressive language and fine motor development assessed using the Bayley-III. Prespecified intent-to-treat analysis investigated impacts and heterogeneity by gender. Trial registrations: ISRCTN89476603, AEARCTR-0000169.
Results: Endline data for 378 (89.8%) children were analysed. Attrition was balanced between groups. We found improvements of 0.349 of a standard deviation (SD; p = .005, stepdown p = .017) to cognition while impacts on receptive language, expressive language and fine motor development were, respectively, 0.224 SD (p = .099, stepdown p = .184), 0.192 SD (p = .085, stepdown p = .184) and 0.111 (p = .385, stepdown p = .385). A child development factor improved by 0.301 SD (p = .032). Benefits were larger for boys. The quality of the home stimulation environment also improved.
Conclusions: This study shows that a potentially scalable home-visiting intervention is effective in poor urban areas.

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Abstract: Based on an RCT, we evaluate a scholarship program in Mexico (PROBEMS) aimed at improving graduation rates and test scores among upper secondary school students from poor backgrounds. We find that, on average, the program has no impact either on graduation rates or on Math and Spanish test scores. We point to two possible reasons for this failure: a. the program was badly targeted, with many of the recipients being from less disadvantaged families than intended; b) the prior academic achievement of those eligible was often insufficient for completing successfully the academic requirements of upper secondary school. This points to accumulated achievement deficits that could be addressed by interventions targeting learning at an earlier stage.

Abstract: Using a representative sample of 1,962 parents in England, we study how parents perceive the returns to parental time investments, material investments and school quality. Parents perceive the returns to 3h of weekly time investments or £30 of weekly material investments to matter more than moving a child to a better school. Material investments are perceived as more productive if children attend higher quality schools. Perceived returns do not differ with the child’s initial human capital or gender, and they are highly correlated with actual investment decisions.

Abstract: A key challenge in developing countries interested in providing early childhood development (ECD) programmes at scale is whether these programmes can be effectively delivered through existing public service infrastructures. We present the results of a randomised experiment evaluating the effects of a home-based parenting programme delivered by cadres in China’s Family Planning Commission (FPC)—the former enforcers of the one-child policy. We find that the programme significantly increased infant skill development after six months and that increased investments by caregivers alongside improvements in parenting skills were a major mechanism through which this occurred. Children who lagged behind in their cognitive development and received little parental investment at the onset of the intervention benefited most from the programme. Household participation in the programme was associated with the degree to which participants had a favourable view of the FPC, which also increased due to the programme.

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Objective: We aimed to determine the timing and size of the cognitive deficit associated with poverty in the first 5 years of life and to examine the role of parental characteristics, pre- and postnatal growth, and stimulation in the home in Bangladeshi children. We hypothesized that the effect of poverty on cognition begins in infancy and is mainly mediated by these factors.
Methods: We enrolled 2853 singletons, a subsample from a pregnancy supplementation trial in a poor rural area. We assessed mental development at 7, 18, and 64 months; anthropometry at birth, 12, 24, and 64 months; home stimulation at 18 and 64 months; and family’s socioeconomic background. In multiple regression analyses, we examined the effect of poverty at birth on IQ at 64 months and the extent that other factors mediated the effect.
Results: A mean cognitive deficit of 0.2 (95% confidence interval –0.4 to –0.02) z scores between the first and fifth wealth quintiles was apparent at 7 months and increased to 1.2 (95% confidence interval –1.3 to –1.0) z scores of IQ by 64 months. Parental education, pre- and postnatal growth in length, and home stimulation mediated 86% of the effects of poverty on IQ and had independent effects. Growth in the first 2 years had larger effects than later growth. Home stimulation had effects throughout the period.
Conclusions: Effects of poverty on children’s cognition are mostly mediated through parental education, birth size, growth in the first 24 months, and home stimulation in the first 5 years.