Nurturing care: promoting early childhood development.

The UN Sustainable Development Goals provide a historic opportunity to implement interventions, at scale, to promote early childhood development. Although the evidence base for the importance of early childhood development has grown, the research is distributed across sectors, populations, and settings, with diversity noted in both scope and focus. We provide a comprehensive updated analysis of early childhood development interventions across the five sectors of health, nutrition, education, child protection, and social protection. Our review concludes that to make interventions successful, smart, and sustainable, they need to be implemented as multi-sectoral intervention packages anchored in nurturing care. The recommendations emphasise that intervention packages should be applied at developmentally appropriate times during the life course, target multiple risks, and build on existing delivery platforms for feasibility of scale-up. While interventions will continue to improve with the growth of developmental science, the evidence now strongly suggests that parents, caregivers, and families need to be supported in providing nurturing care and protection in order for young children to achieve their developmental potential.

Inequality in early childhood: risk and protective factors for early child development.

Inequality between and within populations has origins in adverse early experiences. Developmental neuroscience shows how early biological and psychosocial experiences affect brain development. We previously identified inadequate cognitive stimulation, stunting, iodine deficiency, and iron-deficiency anaemia as key risks that prevent millions of young children from attaining their developmental potential. Recent research emphasises the importance of these risks, strengthens the evidence for other risk factors including intrauterine growth restriction, malaria, lead exposure, HIV infection, maternal depression, institutionalisation, and exposure to societal violence, and identifies protective factors such as breastfeeding and maternal education. Evidence on risks resulting from prenatal maternal nutrition, maternal stress, and families affected with HIV is emerging. Interventions are urgently needed to reduce children's risk exposure and to promote development in affected children. Our goal is to provide information to help the setting of priorities for early child development programmes and policies to benefit the world's poorest children and reduce persistent inequalities.

Infant Nutrition and 12 and 18 Months Secure Base Behavior: An Exploratory Study.

A notable omission in studies of developmental links to early nutritional deficiencies is infant attachment. In those few studies investigating associations between infant nutrition and attachment, nutrition was defined solely by physical growth, and infants had moderate-severe growth retardation. In this study, we utilized multiple markers of infant nutrition. Our sample consisted of 172 12-month-old Peruvian infants and their mothers from low-income families, with a follow-up assessment on 77 infants at 18 months. Infants were not severely malnourished, but did have micronutrient deficiencies. Anthropometry, dietary intake, and iron status were used as measures of infant nutrition. Based on infant behavior in a structured laboratory situation, Q-sort techniques were used to rate three attachment markers: infant secure base behavior, interaction quality, and negative emotionality with mother. At 12 months, infant weight was positively related to interaction quality. At 18 months, infant iron status was positively related to secure base behavior. This pattern of findings remained even after statistically controlling for family socioeconomic status and maternal education. Our findings indicate that infant nutritional status is associated with markers of infant attachment and these associations are not restricted just to severely malnourished infants.

Child development: risk factors for adverse outcomes in developing countries.

Poverty and associated health, nutrition, and social factors prevent at least 200 million children in developing countries from attaining their developmental potential. We review the evidence linking compromised development with modifiable biological and psychosocial risks encountered by children from birth to 5 years of age. We identify four key risk factors where the need for intervention is urgent: stunting, inadequate cognitive stimulation, iodine deficiency, and iron deficiency anaemia. The evidence is also sufficient to warrant interventions for malaria, intrauterine growth restriction, maternal depression, exposure to violence, and exposure to heavy metals. We discuss the research needed to clarify the effect of other potential risk factors on child development. The prevalence of the risk factors and their effect on development and human potential are substantial. Furthermore, risks often occur together or cumulatively, with concomitant increased adverse effects on the development of the world's poorest children.

Multiple influences on children's nutritional deficiencies: a systems perspective.

Under-nutrition and obesity are multi-determined. The multiple determinants of either under-nutrition or obesity are linked, thus forming a system of influences. How a system of linked multiple influences functions is illustrated with specific reference to early nutritional deficiencies. The traditional explanation that child nutritional deficiencies are due to food scarcity or a lack of family economic resources has been increasingly questioned. In the UNICEF extended care model, deficiencies in children's nutritional intake are due to family economic and food resources and to specific caregiver resources. The role of three caregiver resources, maternal education, intelligence and depression are reviewed. Evidence also is presented on the need to take into account child characteristics, as an additional set of influences on nutritional deficiencies. Using a systems perspective this review documents how the relation to nutrition of family and caregiver resources and child characteristics can be mediated or moderated by alternative linked influences such as cultural characteristics, maternal input into family economic decisions and social support networks. Based on this review a revised extended care model is presented, explicitly integrating child characteristics and specific mediating and moderating links between multiple predictors of child nutritional deficiencies. This is followed by a brief discussion on how a systems perspective can also apply to the study of childhood obesity.

Intra-individual variability in infancy: structure, stability, and nutritional correlates.

Intra-individual variability (IIV) refers to relatively stable differences between individuals in the degree to which they show behavioral fluctuations over relatively short time periods. Using temperament as a conceptual framework the structure, stability, and biological roots of IIV were assessed over the first year of life. Biological roots were defined by maternal and infant nutrition. The sample was 249 Peruvian neonates, followed from the second trimester of pregnancy through the first 12 months of life. Maternal anthropometry, diet, iron status, and fetal growth were assessed prenatally. Neonatal anthropometry and iron status were assessed at birth. Degree of exclusive breastfeeding was assessed at 3 and 6 months, infant anthropometry was assessed at 3, 6, and 12 months, infant dietary intake was assessed at 6 and 12 months and infant iron status was tested at 12 months. Individual differences in IIV at 3, 6, and 12 months were derived from a residual standard deviation score based on infant behaviors measured using the Louisville Temperament Assessment Procedure. Principal components analysis indicated that individual differences in IIV were defined by two components at 3, 6, and 12 months. There was modest stability between IIV components assessed at 3 and 12 months. Reduced levels of IIV at 3 months were predicted by higher maternal weight and higher fetal weight gains in the first and second trimesters of pregnancy. Higher levels of IIV at 3 months were predicted by higher levels of maternal hemoglobin during pregnancy and higher levels of neonatal ferritin.

Contributions of temperament to buffering and sensitization processes in children's development.

Temperament refers to relatively stable, early appearing, biologically rooted individual differences in behavioral traits. Individual differences in temperament are multidetermined encompassing both biological and experiential influences. Evidence indicates that certain temperament traits, such as impulsivity, inhibition, and negative emotionality, can serve as developmental risk factors. Evidence also indicates that other temperament traits, such as flexible self-regulation, sociability, and task orientation, can serve to increase children's resilience. Five potential mechanisms through which individual differences in temperament can increase vulnerability or facilitate resilience are presented: (1) Differential treatment of children with different temperaments by caregivers or teachers (reactive covariance). (2) Children with different temperament styles seeking out environments that may increase risk or promote resilience (active covariance). (3) Goodness or poorness of fit between child temperament characteristics and environmental demands. (4) Children with different temperaments reacting to similar levels or types of stress in different ways. (5) Different coping strategies used by children with different temperaments.

Hershey Medical Center Technical Workshop Report: optimizing the design and interpretation of epidemiologic studies for assessing neurodevelopmental effects from in utero chemical exposure.

Neurodevelopmental disabilities affect 3-8% of the 4 million babies born each year in the U.S. alone, with known etiology for less than 25% of those disabilities. Numerous investigations have sought to determine the role of environmental exposures in the etiology of a variety of human neurodevelopmental disorders (e.g., learning disabilities, attention deficit-hyperactivity disorder, intellectual disabilities) that are manifested in childhood, adolescence, and young adulthood. A comprehensive critical examination and discussion of the various methodologies commonly used in investigations is needed. The Hershey Medical Center Technical Workshop: Optimizing the design and interpretation of epidemiologic studies for assessing neurodevelopmental effects from in utero chemical exposure provided such a forum for examining these methodologies. The objective of the Workshop was to develop scientific consensus on the key principles and considerations for optimizing the design and interpretation of epidemiologic studies of in utero exposure to environmental chemicals and subsequent neurodevelopmental effects. (The Panel recognized that the nervous system develops post-natally and that critical periods of exposure can span several developmental life stages.) Discussions from the Workshop Panel generated 17 summary points representing key tenets of work in this field. These points stressed the importance of: a well-defined, biologically plausible hypothesis as the foundation of in utero studies for assessing neurodevelopmental outcomes; understanding of the exposure to the environmental chemical(s) of interest, underlying mechanisms of toxicity, and anticipated outcomes; the use of a prospective, longitudinal cohort design that, when possible, runs for periods of 2-5 years, and possibly even longer, in an effort to assess functions at key developmental epochs; measuring potentially confounding variables at regular, fixed time intervals; including measures of specific cognitive and social-emotional domains along with non-cognitive competence in young children, as well as comprehensive measures of health; consistency of research design protocols across studies (i.e., tests, covariates, and analysis styles) in an effort to improve interstudy comparisons; emphasis on design features that minimize introduction of systematic error at all stages of investigation: participant selection, data collection and analysis, and interpretation of results; these would include (but not be limited to) reducing selection bias, using double-blind designs, and avoiding post hoc formulation of hypotheses; a priori data analysis strategies tied to hypotheses and the overall research design, particularly for methods used to characterize and address confounders in any neurodevelopmental study; actual quantitative measurements of exposure, even if indirect, rather than methods based on subject recall; careful examination of standard test batteries to ensure that the battery is tailored to the age group as well as what is known about the specific neurotoxic effects on the developing nervous system; establishment of a system for neurodevelopmental surveillance for tracking the outcomes from in utero exposure across early developmental time periods to determine whether central nervous system injuries may be lying silent until developmentally challenged; ongoing exploration of computerized measures that are culturally and linguistically sensitive, and span the age range from birth into the adolescent years; routine incorporation of narrative in manuscripts concerning the possibility of spurious (i.e., false positive and false negative) test results in all research reportage (this can be facilitated by detailed, transparent reporting of design, covariates, and analyses so that others can attempt to replicate the study); forthright, disciplined, and intellectually honest treatment of the extent to which results of any study are conclusive--that is, how generalizable the results of the study are in terms of the implications for the individual study participants, the community studied, and human health overall; confinement of reporting to the actual research questions, how they were tested, and what the study found, and avoiding, or at least keeping to a minimum, any opinions or speculation concerning public health implications; education of clinicians and policymakers to critically read scientific reports, and to interpret study findings and conclusions appropriately; and recognition by investigators of their ethical duty to report negative as well as positive findings, and the importance of neither minimizing nor exaggerating these findings.

Linking nutrition and education: a cross-generation model.

Psychosocial influences, such as the family or the school, and biologic influences, such as nutrition or the presence of environmental toxins, can be viewed as elements of a child's overall environment. Family and school influences define dimensions of the child's psychosocial environment whereas nutrition and exposure to toxins define dimensions of the child's bioecologic environment. This paper presents a cross-generation model specifying both the nature and consequences of linkages between the psychosocial and bioecologic environments, with specific reference to schooling, nutrition, and development. Data from two studies done in Egypt and Peru are used to illustrate this model, showing how duration of breastfeeding and quality of the young child's diet are positively associated with higher levels of maternal education and intelligence.

Issues in the timing of integrated early interventions: contributions from nutrition, neuroscience, and psychological research.

A central issue when designing multidimensional biological and psychosocial interventions for children who are exposed to multiple developmental risks is identification of the age period(s) in which such interventions will have the strongest and longest lasting effects (sensitive periods). In this paper, we review nutritional, neuroscientific, and psychological evidence on this issue. Nutritional evidence is used to identify nutrient-sensitive periods of age-linked dimensions of brain development, with specific reference to iron deficiency. Neuroscience evidence is used to assess the importance of timing of exposures to environmental stressors for maintaining neural, neuroendocrine, and immune systems integrity. Psychological evidence illustrates the sensitivity of cognitive and social-emotional development to contextual risk and protective influences encountered at different ages. Evidence reviewed documents that the early years of life are a sensitive period when biological or psychosocial interventions or exposure to risk or protective contextual influences can produce unique long-term influences upon human brain, neuroendocrine, and cognitive or psychosocial development. However, the evidence does not identify the early years as the sole sensitive time period within which to have a significant influence upon development. Choice of age(s) to initiate interventions should be based on what outcomes are targeted and what interventions are used.

Models linking nutritional deficiencies to maternal and child mental health.

The primary goal of this article was to illustrate how nutritional deficiencies can translate into adult or child mental health problems. Whereas brain development and function play an essential role in the etiology and maintenance of mental health problems, what is required are models that go beyond nutrition-brain relations and integrate the contributions of nutritionally related contextual and behavioral characteristics. Four such models are presented. The multiple risks model derives from evidence showing covariance between nutritional deficiencies and other life stressors. Given that poorly nourished adults may be less able to actively cope with stressors, nutritional deficiencies may accentuate the negative impact of stress exposure on mental health. The cross-generational model is based on evidence showing less adequate patterns of mother-child interactions when mothers are poorly nourished. Impairments in mother-child interactions increase the likelihood of child mental health problems and the risk of subsequent child nutritional deficiencies. The attachment model derives from evidence showing that poorly nourished infants may be less likely to elicit the types of maternal child-rearing patterns that translate into secure infant-mother attachments. Insecure attachments in infancy are associated with an increased risk of both short-term and long-term child mental health problems. The temperament model is based on evidence documenting that certain patterns of infant temperament are related to an increased risk of later behavioral problems. Infant nutritional deficiencies can influence the development of temperament, and certain temperament patterns can contribute to an increased risk of infant nutritional deficiencies.

Relation of neonatal iron status to individual variability in neonatal temperament.

The relation between indices of neonatal iron status and individual differences in neonatal temperament were investigated in a sample of 148 low-income Peruvian women and their newborn infants. Using cord blood, at birth we obtained measures of neonatal ferritin, serum iron, and hemoglobin. While neonates were still in the hospital, their behavior during a structured anthropometry examination was videotaped and subsequently coded on four temperament dimensions: activity level, negative emotionality, alertness, and soothability. The same dimensions were coded using a videotape obtained during a subsequent visit to the neonates' homes. Results indicated that lower levels of neonatal hemoglobin and serum iron were related to higher levels of negative emotionality and to lower levels of alertness and soothability. A similar pattern was found for ferritin, but only for females. For the most part, relations between neonatal iron measures and neonatal temperament were linear, operating across the full range of iron values. Our pattern of iron-temperament results could not be attributed to variation in family demographics, low birth weight, gestational age, maternal dietary intake, or markers of neonatal illness and maternal diabetes. Our findings are consistent with prior research with older infants relating iron deficiency to temperament. These results support the importance of increased research on the early functional-behavioral consequences of individual differences in iron status as well as on the mechanisms that underlie such consequences.

Maternal education and intelligence predict offspring diet and nutritional status.

The traditional assumption that children's nutritional deficiencies are essentially due either to overall food scarcity or to a lack of family resources to purchase available food has been increasingly questioned. Parental characteristics represent 1 type of noneconomic factor that may be related to variability in children's diets and nutritional status. We report evidence on the relation of 2 parental characteristics, maternal education level and maternal intelligence, to infant and toddler diet and nutritional status. Our sample consisted of 241 low-income Peruvian mothers and their infants assessed from 3 to 12 mo, with a further follow-up of 104 of these infants at 18 mo of age. Using a nonexperimental design, we related measures of level of maternal education, maternal intelligence, and family socioeconomic status to infant anthropometry, duration of exclusive breast-feeding, adequacy of dietary intake, and iron status. Results indicated unique positive relations between maternal education level and the extent of exclusive breast-feeding. Significant relations between maternal education and offspring length were partially mediated by maternal height. There also were unique positive relations between maternal intelligence and quality of offspring diet and hemoglobin level. All findings remained significant even after controlling for family socioeconomic characteristics. This pattern of results illustrates the importance of parental characteristics in structuring the adequacy of offspring diet. Maternal education and intelligence appear to have unique influences upon different aspects of the diet and nutritional status of offspring.