Andreas Georgiadis

Postinfancy growth, schooling, and cognitive achievement: Young Lives

Background: Early life growth failure and resulting cognitive deficits are often assumed to be very difficult to reverse after infancy. Objective: We used data from Young Lives, which is an observational cohort of 8062 children in Ethiopia, India, Peru, and Vietnam, to determine whether changes in growth after infancy are associated with schooling and cognitive achievement at age 8 y. Design: We represented the growth by height-for-age z score at 1 y [HAZ(1)] and height-for-age z score at 8 y that was not predicted by the HAZ(1). We also characterized growth as recovered (stunted at age 1 y and not at age 8 y), faltered (not stunted at age 1 y and stunted at age 8 y), persistently stunted (stunted at ages 1 and 8 y), or never stunted (not stunted at ages 1 and 8 y). Outcome measures were assessed at age 8 y. Results: The HAZ(1) was inversely associated with overage for grade and positively associated with mathematics achievement, reading comprehension, and receptive vocabulary. Unpredicted growth from 1 to 8 y of age was also inversely associated with overage for grade (OR range across countries: 0.80–0.84) and positively associated with mathematics achievement (effect-size range: 0.05–0.10), reading comprehension (0.02–0.10), and receptive vocabulary (0.04–0.08). Children who recovered in linear growth had better outcomes than did children who were persistently stunted but were not generally different from children who experienced growth faltering. Conclusions: Improvements in child growth after early faltering might have significant benefits on schooling and cognitive achievement. Hence, although early interventions remain critical, interventions to improve the nutrition of preprimary and early primary school–age children also merit consideration.

Growth faltering and recovery in children aged 1-8 years in four low- and middle-income countries: Young Lives

OBJECTIVE We characterized post-infancy child growth patterns and determined the incidence of becoming stunted and of recovery from stunting. DESIGN Data came from Young Lives, a longitudinal study of childhood poverty in four low- and middle-income countries. SETTING We analysed length/height measurements for children at ages 1, 5 and 8 years. SUBJECTS Children (n 7171) in Ethiopia, India, Peru and Vietnam. RESULTS Mean height-for-age Z-score (HAZ) at age 1 year ranged from -1·51 (Ethiopia) to -1·08 (Vietnam). From age 1 to 5 years, mean HAZ increased by 0·27 in Ethiopia (P < 0·001) and decreased among the other cohorts (range: -0·19 (Peru) to -0·32 (India); all P < 0·001). From 5 to 8 years, mean HAZ increased in all cohorts (range: 0·19 (India) to 0·38 (Peru); all P < 0·001). Prevalence of stunting (HAZ<-2·0) at 1 year ranged from 21 % (Vietnam) to 46 % (Ethiopia). From age 1 to 5 years, stunting prevalence decreased by 15·1 percentage points in Ethiopia (P < 0·001) and increased in the other cohorts (range: 3·0 percentage points (Vietnam) to 5·3 percentage points (India); all P ≤ 0·001). From 5 to 8 years, stunting prevalence decreased in all cohorts (range: 5·0 percentage points (Vietnam) to 12·7 percentage points (Peru); all P < 0·001). The incidence of becoming stunted between ages 1 to 5 years ranged from 11 % (Vietnam) to 22 % (India); between ages 5 to 8 years, it ranged from 3 % (Peru) to 6 % (India and Ethiopia). The incidence of recovery from stunting between ages 1 and 5 years ranged from 27 % (Vietnam) to 53 % (Ethiopia); between ages 5 and 8 years, it ranged from 30 % (India) to 47 % (Ethiopia). CONCLUSIONS We found substantial recovery from early stunting among children in four low- and middle-income countries.

Growth trajectories from conception through middle childhood and cognitive achievement at age 8 years: Evidence from four low- and middle-income countries

Child chronic malnutrition is endemic in low- and middle-income countries and deleterious for child development. Studies investigating the relationship between nutrition at different periods of childhood, as measured by growth in these periods (growth trajectories), and cognitive development have produced mixed evidence. Although an explanation of this has been that different studies use different approaches to model growth trajectories, the differences across approaches are not well understood. Furthermore, little is known about the pathways linking growth trajectories and cognitive achievement. In this paper, we develop and estimate a general path model of the relationship between growth trajectories and cognitive achievement using data on four cohorts from Ethiopia, India, Peru, and Vietnam. The model is used to: (a) compare two of the most common approaches to modelling growth trajectories in the literature, namely the lifecourse plot and the conditional body size model, and (b) investigate the potential channels via which the association between growth in each period and cognitive achievement manifests. We show that the two approaches are expected to produce systematically different results that have distinct interpretations. Results suggest that growth from conception through age 1 year, between age 1 and 5 years, and between 5 and 8 years, are each positively and significantly associated with cognitive achievement at age 8 years and that this may be partly explained by the fact that faster-growing children start school earlier. We also find that a significant share of the association between early growth and later cognitive achievement is mediated through growth in interim periods.

Growth Recovery and Faltering through Early Adolescence in Low- and Middle-Income Countries: Determinants and Implications for Cognitive Development

Child chronic undernutrition, as measured by stunting, is prevalent in low- and middle-income countries and is among the major threats to child development. While stunting and its implications for cognitive development have been considered irreversible beyond early childhood there is a lack of consensus in the literature on this, as there is some evidence of recovery from stunting and that this recovery may be associated with improvements in cognition. Less is known however, about the drivers of growth recovery and the aspects of recovery linked to cognitive development. In this paper we investigate the factors associated with growth recovery and faltering through age 12 years and the implications of the incidence, timing, and persistence of post-infancy recovery from stunting for cognitive development using longitudinal data from Ethiopia, India, Peru, and Vietnam. We find that the factors most systematically associated with accelerated growth both before and after early childhood and across countries include mothers height, household living standards and shocks, community wages, food prices, and garbage collection. Our results suggest that post-infancy recovery from stunting is more likely to be systematically associated with higher achievement scores across countries when it is persistent and that associations between growth trajectories and cognitive achievement in middle childhood do not persist through early adolescence across countries. Overall, our findings indicate that growth after early childhood is responsive to changes in the household and community environments and that growth promotion after early childhood may yield improvements in child cognitive development.

Child undernutrition: opportunities beyond the first 1000 days

Stunting—an indicator of linear growth retardation that results in low height-for-age—reflects poor growth and development in children, which is a major public health concern in developing countries. Stunting often begins in utero and increases, on average, for at least the first 2 years after birth. The first 1000 days between conception and a child’s second birthday has been identified as the most crucial window of opportunity for interventions. Evidence suggests that stunting is largely irreversible after the first 1000 days, leading to an intergenerational cycle of poor growth and development, in which women who were stunted in childhood remain stunted as adults and tend to have stunted offspring. However, evidence indicates that accelerated linear growth in childhood and adolescence following stunting in infancy (ie, catchup growth) can occur. Evidence from the Young Lives international cohort study in Ethiopia, India, Peru, and Vietnam, found that around 50% of children who were stunted at age 1 year showed improvements in height and were no longer stunted at age 8 years in the absence of an intervention. Other longitudinal observational studies have also reported catch-up growth in childhood. Could adolescence represent a crucial window for interventions after the first 1000 days? In particular, interventions that improve the nutritional status of adolescent girls, a group that is especially susceptible to the effects of undernutrition, could potentially break the intergenerational cycle of poor growth and development in lowincome and middle-income countries. However, the mechanism by which intergenerational benefits might be realised through interventions at this age is unclear. Moreover, whether these benefits might result from interventions that promote catch-up growth in adolescent girls remains unknown. This uncertainty exists despite the argument that adolescence—a period characterised by rapid growth that is second only to that of infancy—presents an opportunity for catch-up growth and greater adult height, and that improved adult height in mothers is expected to lead to better outcomes in offspring. Evidence has provided support for these hypotheses. For example, analysis of Young Lives data shows that among 12-year-old girls with height below the WHO standard for their age group, on average, 40% of the height deficit was recovered by age 19 years. Furthermore, children with mothers who were stunted as adults were about 15% more likely to be stunted as infants and to remain stunted through early adolescence than children with mothers who were not stunted as adults. Another important question for policy is whether improvements in nutrition beyond the first 1000 days do not only remedy growth, but also deficits in cognitive development that are associated with early undernutrition. Some evidence from observational studies supports an association between accelerated growth in childhood and adolescence and cognitive achievement. Indeed, among children who were stunted at age 1 year, those who were not stunted at age 8 years performed better in achievement tests compared with children who were stunted at both ages. However, a few studies have assessed the effect of recovery from stunting on cognitive achievement in children aged between 5 and 8 years and evidence from existing studies has been mixed. A meta-analysis showed that nutrition interventions had a positive effect after age 2 years, but this effect was considerably smaller than the effect of interventions before age 2 years. More research is needed to establish a causal link between catchup growth after the first 1000 days and cognitive development. Although the first 1000 days is a crucial stage for future growth and development and the most important period for interventions against stunting, accelerated linear growth can occur at later ages and might reverse stunting, particularly during adolescence, and this might present another opportunity for interventions aiming to break the intergenerational cycle of child undernutrition.

Family Socio-economic Status, Mother’s Psychosocial Skills, and Children’s Human Capital: Evidence from Four Low- and Middle-income Countries

Family background has been considered one of most important factors associated with child development across different settings (Brooks-Gunn and Duncan 1997; Grantham-McGregor et al. 2007). Evidence from industrialized countries supports a strong link between different background factors, such as parental socio-economic status (SES), and parental cognitive and psychosocial skills on the one hand, and children’s cognitive and psychosocial skills on the other; these factors in turn are important determinants of educational achievement, earnings, and other key outcomes in later life (Osborne-Groves 2005a; Cunha et al. 2006; Blanden et al. 2007).

Disparities in Children’s Vocabulary and Height in Relation to Household Wealth and Parental Schooling: A Longitudinal Study in Four Low- and Middle-Income Countries

Children from low socio-economic status (SES) households often demonstrate worse growth and developmental outcomes than wealthier children, in part because poor children face a broader range of risk factors. It is difficult to characterize the trajectories of SES disparities in low- and middle-income countries because longitudinal data are infrequently available. We analyze measures of children’s linear growth (height) at ages 1, 5, 8 and 12y and receptive language (Peabody Picture Vocabulary Test) at ages 5, 8 and 12y in Ethiopia, India, Peru and Vietnam in relation to household SES, measured by parental schooling or household assets. We calculate children’s percentile ranks within the distributions of height-for-age z-scores and of age- and language-standardized receptive vocabulary scores. We find that children in the top quartile of household SES are taller and have better language performance than children in the bottom quartile; differences in vocabulary scores between children with high and low SES are larger than differences in the height measure. For height, disparities in SES are present by age 1y and persist as children age. For vocabulary, SES disparities also emerge early in life, but patterns are not consistent across age; for example, SES disparities are constant over time in India, widen between 5 and 12y in Ethiopia, and narrow in this age range in Vietnam and Peru. Household characteristics (such as mother’s height, age, and ethnicity), and community fixed effects explain most of the disparities in height and around half of the disparities in vocabulary. We also find evidence that SES disparities in height and language development may not be fixed over time, suggesting opportunities for policy and programs to address these gaps early in life.