Global, regional and country trends in underweight and stunting as indicators of nutrition and health of populations.

Stunting and wasting provide indicators of different nutritional deficiency problems, the causes of which are well established. Underweight based on weight-for-age cannot distinguish between these two and is therefore not useful to target programs and has limited value for tracking progress. Stunting reduces later school attainment and income as adults and increases the risk of obesity and noncommunicable diseases in later life. Globally, the estimated number of stunted children is decreasing, but is not on track to meet the goal of 100 million by 2025 (165 million), and there has been little change in the number of children suffering from wasting since 2004. Stunting and wasting provide excellent indicators of inequity. For example, from 1990 to 2010, the number of stunted children in Asia declined from 188.7 to 98.4 million, while in sub-Saharan Africa there was essentially no change in prevalence, and the number of stunted children increased from 45.7 to 55.8 million. Recent global development movements are recognizing the need for robust measures of trends in nutritional status of children, particularly during the critical first years of life. Such measures are needed to track progress and improve accountability, and should be aspirational to mobilize sufficient investment in nutrition.

Early life growth trajectories and future risk for overweight.

OBJECTIVE: Standard approaches have found that rapid growth during the first 2 years of life is a risk factor for overweight in later childhood. Our objective was to test whether growth velocity, independent of concurrent size, was associated with overweight using a nonlinear random-effects model that allows for enhanced specifications and estimations. METHODS: Longitudinal data from a birth cohort in Mexico (n=586) were used to estimate growth trajectories over 0-24 months for body mass index (BMI), length and weight using the SuperImposition by Translation and Rotation (SITAR) models. The SITAR models use a nonlinear random-effects model to estimate an average growth curve for BMI, length and weight and each participant's deviation from this curve on three dimensions-size, velocity and timing of peak velocity. We used logistic regression to estimate the association between overweight status at 7-9 years and size, velocity and timing of BMI, length and weight trajectories during 0-24 months. We tested whether any association between velocity and overweight varied by relative size during 0-24 months or birth weight. RESULTS: SITAR models explained the majority of the variance in BMI (73%), height (86%) and weight (85%) between 0-24 months. When analyzed individually, relative BMI/length/weight (size) and BMI/length/weight velocity during 0-24 months were each associated with increased odds of overweight in late childhood. Associations for timing of peak velocity varied by anthropometric measure. However, in the mutually adjusted models, only relative BMI/length/weight (size) remained statistically significant. We found no evidence that any association between velocity and overweight varied by size during 0-24 months or birth weight. CONCLUSIONS: After mutual adjustment, size during 0-24 months of life (as opposed to birth size), but not velocity or timing of peak velocity, was most consistently associated with overweight in later childhood.

Disproportionate early fetal growth predicts postnatal thymic size in humans.

Prenatal events can affect neonatal thymus size and adult immune function. The causal insults are unknown, although fetal nutrient restriction is suspected. We used ultrasound at three time points during pregnancy (14, 19 and 30 weeks) to measure the growth of six fetal dimensions in rural Bangladeshi women participating in the Maternal and Infant Nutrition Interventions, Matlab study. Postnatal ultrasound was used to calculate thymic index (TI) at birth, 2, 6 and 12 m. Of the 3267 women recruited, 2861 participated by providing data at least at one fetal biometry and one TI time point. Patterns of fetal growth were summarized using principal components calculated from fetal dimension z-scores. Random effects regression, controlling for infant size and season of measurement were used to relate these patterns to TI. We found that smaller leg length relative to head circumference, characteristic of head-sparing growth restriction, was predictive of lower TI. This association was significant at all time points but strongest in earlier pregnancy. Each standard deviation increase in leg-head proportion was associated with an increase in TI of ∼5%. We conclude that growth patterns typical of poor fetal nutrition are associated with poor thymic development. The greater strength of this association in the first trimester is consistent with a period of vulnerability during the early ontogeny of the thymus and suggests that preventative intervention would need to be given in early pregnancy.

The effect of nutritional supplementation on physical activity and exploratory behavior of Mexican infants aged 8-12 months.

BACKGROUND/OBJECTIVES: Physical activity and exploration in infancy affect physical and cognitive development. Nutritional supplementation improves activity in severely malnourished infants, but the evidence in mild-to-moderately malnourished and nutritionally at-risk infants is equivocal. We tested the effect of multiple-micronutrient supplementation on physical activity and exploration in Mexican infants. SUBJECTS/METHODS: Using a quasi experimental design, we analyzed data from a supplementation study that lacked a placebo-control group. We compared infants between 8 and 12 months measured at baseline who had received no supplementation (comparison group, n=78), with infants 8-12 months measured after 4 months of daily supplementation (treatment group, n=109). The treatment consisted of three supplement types: micronutrient powder, syrup (each containing only micronutrients) and a milk-based, fortified-food supplement (FFS; containing micronutrients and macronutrients). We formed the micronutrient-only group (MM) by combining the micronutrient powder and syrup groups. We measured activity and exploration by direct observation and used cluster analysis to form and characterize activity and exploration clusters. We performed logistic regression with activity or exploration cluster as the outcome variable and treatment versus comparison and MM or FFS versus comparison as the predictor variables. RESULTS: Treatment versus comparison increased the odds of being in the high activity (odds ratio (OR)=2.35, P<0.05) and high exploration (OR=1.87, P<0.05) cluster. MM increased the odds of being in the high activity (OR=2.64, P<0.05) cluster and FFS increased the odds (OR=3.16, P<0.05) of being in the high exploration cluster. CONCLUSIONS: Nutritional supplementation benefited activity and exploration in this sample of Mexican infants.

Measurement error for ultrasound fetal biometry performed by paramedics in rural Bangladesh.

OBJECTIVES: To document the accuracy and precision of sonographic fetal biometry performed by nine paramedics from rural Bangladesh. METHODS: Paramedics underwent intensive training (6 weeks) including hands-on practice then underwent a series of standardization exercises. Measurements of each fetus were taken by a highly-trained medical doctor (study supervisor) and the nine paramedics. Crown-rump length (CRL) in fetuses of less than 10 weeks' gestation, and biparietal diameter (BPD), occipitofrontal diameter, head and abdominal circumference (AC) and femur diaphysis length (FL) were measured twice using standard procedures by each paramedic and the medical doctor for each fetus, with at least 20 min between them. Precision was quantified using variance components analysis; the intraobserver error for each of the paramedics was calculated by comparing repeat measurements taken on the same participant, and the measurements obtained by each individual paramedic were also compared with those taken by the others (interobserver error). Accuracy was estimated by comparing the mean of the two measures taken by each paramedic to those taken by the study supervisor using paired t-tests. Bland-Altman plots were used to visually assess the relationship between precision of repeat measurements (intraobserver error) and fetal size. RESULTS: A total of 180 women, at 7 to 31 weeks' gestation, participated in the study. Intraobserver error of the measurements obtained by the paramedics, expressed as the mean SD, ranged from 0.97 mm for BPD in the first trimester to 7.25 mm for AC in the third trimester, and was larger than the interobserver error (i.e. accounting for a greater proportion of total variance) for most measurements. Interobserver error ranged from 0.00 mm for FL to 3.36 mm for AC, both in the third trimester. For all measurements except CRL, intraobserver error increased with increasing fetal size. The measurements obtained by the paramedics did show some statistically significant differences from those obtained by the study supervisor, but these were relatively small in magnitude. CONCLUSIONS: Both inter- and intraobserver measurement errors were within the range reported in the literature for studies conducted by technical staff and medical doctors. With intense training, paramedics with no prior exposure to ultrasonography can provide accurate and precise measures of fetal biometry.

Overweight with concurrent stunting in very young children from rural Mexico: prevalence and associated factors.

OBJECTIVE: To document the prevalence of overweight or obesity concurrent with stunting in rural low-income Mexican children and to identify demographic and socio-economic characteristics that could help identify families at risk of having an overweight/obese and stunted young child in this population. DESIGN: Cross-sectional analysis of the nutritional status of very young children, using primary data from a rural community-based survey conducted in 2003. Overweight, obesity and stunting were documented along with several maternal, household and community characteristics. SETTING: Impoverished areas of rural Mexico. SUBJECTS: Pre-school children (n=7555), aged 24-72 months. RESULTS: The combined prevalence of overweight and obesity was equal to or greater than 20% in all children, as was the prevalence of stunting. The prevalence of concurrent overweight or obesity and stunting was approximately 5% in non-indigenous children, and over 10% in indigenous children 24-60 months. A multinomial logistic analysis revealed that the factors associated with coexisting stunting and overweight/obesity were lower socio-economic status (SES), lower maternal age, education, intelligence (vocabulary) and perceived social status, shorter maternal height, and larger household size. Among only stunted children, the risk of also being overweight or obese was associated with younger maternal age (relative risk ratios (RRR): 0.98, P=0.05), lower maternal perceived social status (RRR: 0.95, P<0.01) and maternal obesity (RRR: 2.93, P<0.0001) or overweight (RRR: 1.50, P=0.002). CONCLUSIONS: These analyses highlight that concurrent overweight or obesity and stunting is an important public health issue in low-income areas of rural Mexico beginning in early childhood. Even within this impoverished population, children living in households with low relative SES are the most vulnerable. SPONSORSHIP: Financial support for this research was provided by the National Institutes of Child Health and Human Development, the Fogarty International Center at NIH, the John D and Catherine T MacArthur Foundation 'Research Network on Socioeconomic Status and Health' and the Mexican Government.

Ultrasound measurement of fetal size in rural Guatemala.

OBJECTIVES: To describe the fetal growth pattern of a population from rural Guatemala and determine when during gestation growth faltering becomes evident. METHODS: Ultrasound examinations were conducted for 319 women. Femur length (FL), biparietal diameter (BPD), abdominal (AC) and head circumference (HC) were compared with reference values. RESULTS: FL and AC were similar to reference values throughout gestation. BPD and HC were below the 50th percentile by 30 weeks' gestation and below the 10th percentile later in gestation. We expected all four dimensions to show marked growth restriction during gestation. Measurement differences may explain the results but would call into question the value of cross-study comparisons. Infants born small for gestational age were small in all measures as early as 15 weeks. CONCLUSIONS: Fetal growth faltering begins in early gestation among infants who were born small. The lack of deviation from reference data for FL and AC requires further clarification.