The use of national sample surveys for nutritional surveillance: Lessons from Malawi's national sample survey of agriculture

Background Underweight occurs when caloric intake is insufficient to maintain growth. While it has long been assumed that underweight in the first 2 years of life is associated with lower growth potential in later childhood, longer term growth outcomes in high income countries are unclear. Objectives The primary objective was to evaluate the relationship between underweight in the first 2 years of life and body mass index z-score (zBMI) in later childhood. Secondly, we examined the relationship between underweight in the first 2 years of life and weight-for-age z-score (WAZ) and height-for-age z-score (HAZ) in later childhood, and how sex and the zBMI growth trajectory in the first 2 years of life modify these associations. Design/Methods This was a prospective cohort study conducted through The Applied Research Group for Kids (TARGetKids!) practice-based research network. Healthy children 0-10 years of age were included. The primary exposure was underweight in the first 2 years of life using zBMI <-2 as per the World Health Organization (WHO). The primary outcome was zBMI, and secondary outcomes were WAZ and HAZ between 2 and 10 years of age. Linear mixed effects models were used for the primary and secondary analysis to take into account multiple growth measures over time. Interaction terms for sex, and the zBMI growth trajectory in the first 2 years of life were used to explore effect modification. Results Among the 5,803 children included in the primary analysis, the mean age was 4.07 months, and 52.2% were male at baseline. In adjusted models, underweight in the first 2 years of life was associated with lower zBMI, lower WAZ, and higher odds of underweight at 2, 5, and 10 years of age (p <0.0001). Underweight in the first 2 years was associated with a lower HAZ at 2 years of age (p<0.0001), but not 5 (p=0.08), or 10 years of age (p=0.8). Females with underweight had lower zBMI and WAZ at 5 and 10 years of age, and lower HAZ at 10 years of age compared to males with underweight (p<0.05). Children with underweight and lower growth trajectory in the first 2 years had lower zBMI, WAZ, HAZ, and higher odds of underweight at 2, 5, and 10 years of age compared to children who did not have underweight (p<0.05). Children with underweight and high growth trajectory in the first 2 years had similar zBMI, WAZ, higher HAZ and lower odds of overweight at 10 years of age (p<0.05), compared to children who did not have underweight. Conclusion Underweight in the first 2 years of life was associated with lower growth in later childhood. These relationships were amplified for females and children with underweight who had low growth trajectory in the first 2 years of life and were attenuated among children with underweight who had high growth trajectory in the first 2 years of life.

Editor's evaluation: Derivation and external validation of clinical prediction rules identifying children at risk of linear growth faltering

Decision letter: Derivation and external validation of clinical prediction rules identifying children at risk of linear growth faltering

The research explored the association between infants' height and various demographic factors in Romania, a country where such critical information has been lacking. This study was conducted on a nationally representative sample and used a family physicians database to determine a sample of 1532 children (713 girls and 819 boys) 6-23 months of age (M=14.26; SD=5.15). Infants' height-for-age z-scores (HAZ) were calculated using the World Health Organization's computing algorithm. A multiple regression analysis was conducted to investigate whether certain risk factors, such as infant mother's age, location, marital status, socioeconomic status (SES), as well as infant's term status at birth, age, anemia, minimum dietary diversity (MDD) and birth order, could significantly predict the HAZ. The study identified several significant predictors of height. Specifically, lower HAZ was associated with rural living, preterm birth, age 18-23 months, unmarried mothers, anemia, lack of MDD and being third or later born in the family. In contrast, higher HAZ was associated with medium or high maternal SES and older maternal age. The study underscores the importance of addressing these significant risk factors through distinct interventions to improve height outcomes in at-risk Romanian populations.

Stunting is an indicator of poor linear growth in children and is an important public health problem in many countries. Both nutritional deficits and toxic exposures can contribute to lower height-for-age Z-score (HAZ) and stunting (HAZ < -2). In a community-based cross-sectional sample of 97 healthy children ages 6-59 months in Kampala, Uganda, we examined whether exposure to Pb, As, Cd, Se, or Zn were associated with HAZ individually or as a mixture. Blood samples were analyzed for a mixture of metals, which represent both toxins and essential nutrients. The association between HAZ and metal exposure was tested using multivariable linear regression and Weighted Quantile Sum (WQS) regression, which uses mixtures of correlated exposures as a predictor. There were 22 stunted children in the sample, mean HAZ was -0.74 (SD = 1.84). Linear regression showed that Pb (β = -0.80, p = 0.021) and Se (β = 1.92, p = 0.005) were significantly associated with HAZ. The WQS models separated toxic elements with a presumed negative effect on HAZ (Pb, As, Cd) from essential nutrients with presumed positive effect on HAZ (Se and Zn). The toxic mixture was significantly associated with lower HAZ (β = -0.47, p = 0.03), with 62% of the effect from Pb. The nutrient WQS index did not reach statistical significance (β = -0.47, p = 0.16). Higher blood lead and lower blood selenium level were both associated with lower HAZ. The significant associations by linear regression were reinforced by the WQS models, although not all associations reached statistical significance. These findings suggest that healthy children in this neighborhood of Kampala, Uganda, who have a high burden of toxic exposures, may experience detrimental health effects associated with these exposures in an environment where exposure sources are not well characterized.

BackgroundStunting is an indicator of poor linear growth in children and is an important public health problem in many countries. Both nutritional deficits and toxic exposures can contribute to lower height-for-age Z-score (HAZ) and stunting (HAZ < -2).ObjectivesIn a community-based cross-sectional sample of 97 healthy children ages 6–59 months in Kampala, Uganda, we examined whether exposure to Pb, As, Cd, Se, or Zn were associated with HAZ individually or as a mixture.MethodsBlood samples were analyzed for a mixture of metals, which represent both toxins and essential nutrients. The association between HAZ and metal exposure was tested using multivariable linear regression and Weighted Quantile Sum (WQS) regression, which uses mixtures of correlated exposures as a predictor.ResultsThere were 22 stunted children in the sample, mean HAZ was -0.74 (SD = 1.84). Linear regression showed that Pb (β = -0.80, p = 0.021) and Se (β = 1.92, p = 0.005) were significantly associated with HAZ. The WQS models separated toxic elements with a presumed negative effect on HAZ (Pb, As, Cd) from essential nutrients with presumed positive effect on HAZ (Se and Zn). The toxic mixture was significantly associated with lower HAZ (β = -0.47, p = 0.03), with 62% of the effect from Pb. The nutrient WQS index did not reach statistical significance (β = -0.47, p = 0.16).DiscussionHigher blood lead and lower blood selenium level were both associated with lower HAZ. The significant associations by linear regression were reinforced by the WQS models, although not all associations reached statistical significance. These findings suggest that healthy children in this neighborhood of Kampala, Uganda, who have a high burden of toxic exposures, may experience detrimental health effects associated with these exposures in an environment where exposure sources are not well characterized.

IntroductionAlthough boys tend to be more affected by linear growth faltering than girls, little is known about sex differences across distinct age groups. We aimed to compare sex differences in...

BackgroundHeight-for-age z-score (HAZ), based on WHO Child Growth Standards, measures linear growth in children, with lower values indicating potential undernutrition. This study examines HAZ as a continuous measure to explore its proximal and distal determinants.MethodsData from 5,045 children aged 0–59 months from the 2019 Ethiopian Mini Demographic and Health Survey were used. The survey employed a stratified two-stage cluster design. A multilevel mixed-effects linear regression model was applied to estimate the associations between HAZ and various proximal (individual and household-level) and distal (community-level) factors. Proximal factors included child age, sex, early breastfeeding, maternal age, education, age at first birth, maternal literacy, delivery place, number of children under-five, household size, wealth index, media access, household head sex, cooking fuel, toilet type, and water source. Distal factors included urban/rural residence, altitude, and capital city residence. Effect sizes were reported as unstandardized beta coefficients (β) with 95% confidence intervals (CI).ResultsThe mean HAZ was − 1.26 (SD = 1.47). The mean age of the children was 28.9 months, and 36.23% of mothers were literate. Child age was inversely associated with HAZ, with each additional month linked to a 0.02 unit reduction (β = -0.02; 95% CI: -0.024, -0.016; p < 0.001). Maternal age and education were positively associated with HAZ, with each additional year of maternal age linked to a 0.015 unit increase (β = 0.015; 95% CI: 0.003, 0.026; p = 0.012) and each additional year of education associated with a 0.036 unit increase (β = 0.036; 95% CI: 0.009, 0.062; p = 0.008). Higher altitude was associated with a 0.21 unit reduction in HAZ per 1000 m increase (β = -0.21; 95% CI: -0.34, -0.07; p = 0.003). Residence in the capital city was associated with a 0.388 unit increase in HAZ (β = 0.388; 95% CI: 0.093, 0.683; p = 0.01).ConclusionKey determinants of HAZ include child age, maternal age, education, altitude, and capital city residence. These findings highlight the need for multifaceted interventions to improve child linear growth. Enhancing maternal education is a crucial strategy to improve child HAZ scores in Ethiopia.

Objective:The aim of this study was to describe growth during puberty in young people with vertically acquired HIV.Design:Pooled data from 12 paediatric HIV cohorts in Europe and Thailand.Methods:One thousand and ninety-four children initiating a nonnucleoside reverse transcriptase inhibitor or boosted protease inhibitor based regimen aged 1–10 years were included. Super Imposition by Translation And Rotation (SITAR) models described growth from age 8 years using three parameters (average height, timing and shape of the growth spurt), dependent on age and height-for-age z-score (HAZ) (WHO references) at antiretroviral therapy (ART) initiation. Multivariate regression explored characteristics associated with these three parameters.Results:At ART initiation, median age and HAZ was 6.4 [interquartile range (IQR): 2.8, 9.0] years and −1.2 (IQR: −2.3 to −0.2), respectively. Median follow-up was 9.1 (IQR: 6.9, 11.4) years. In girls, older age and lower HAZ at ART initiation were independently associated with a growth spurt which occurred 0.41 (95% confidence interval 0.20–0.62) years later in children starting ART age 6 to 10 years compared with 1 to 2 years and 1.50 (1.21–1.78) years later in those starting with HAZ less than −3 compared with HAZ at least −1. Later growth spurts in girls resulted in continued height growth into later adolescence. In boys starting ART with HAZ less than −1, growth spurts were later in children starting ART in the oldest age group, but for HAZ at least −1, there was no association with age. Girls and boys who initiated ART with HAZ at least −1 maintained a similar height to the WHO reference mean.Conclusion:Stunting at ART initiation was associated with later growth spurts in girls. Children with HAZ at least −1 at ART initiation grew in height at the level expected in HIV negative children of a comparable age.

Early childhood growth faltering is a major public health problem associated with negative short‐and long‐term health and development outcomes. The use of ultrasound technology (US) represents an opportunity for early detection and intervention. The objective of this analysis was to assess if US measurements performed during the second and third trimester of pregnancy predicted child height and stunting at 1 y of age.We used prospective data from women participating in a randomized controlled trial of preconception micronutrient supplementation (PRECONCEPT) in Vietnam (n=1137). Inclusion criteria were having at least one US measurement during the second (n=712) or third trimester (n=798) of pregnancy, singleton birth, and child anthropometric information available at 1 y. Fetal measurements were performed during routine prenatal visits using a portable US machine. US measurements included head circumference, biparietal diameter, abdominal circumference, and femur length which were converted into Z‐scores relative to the INTERGROWTH 21st reference (Zac, Zbp, Zfl, and Zhc respectively). Small for gestational age (SGA) was defined as birth weight below the 10th percentile. Recumbent length was measured at the 1 y postnatal visit and converted into Height for Age Z‐scores (HAZ) relative to the WHO Child Growth Standards and stunting was defined as HAZ &lt; 2 SD. We used multivariate regression models to examine associations between US measurements and stunting/HAZ at 1 y. All models were controlled for socioeconomic status, maternal height, child sex and child age. Results were also stratified by SGA to test if US predictive value was independent of SGA.Mean HAZ at 1 y was −0.85 ± 1.05, and the prevalence of stunting was 13.4%; there were no significant differences by sex. US measurements obtained during the second trimester of pregnancy did not predict HAZ or stunting at 1 y. However, all US measurements obtained during the third trimester were positively associated with HAZ at 1 y. A 1 standard deviation (SD) increase in US z‐scores was associated with 0.12–0.14 SD increase in HAZ (Zac=0.12±0.02; Zbp=0.12±0.03; Zfl=0.14±0.02; Zhc=0.14±0.03, p&lt;0.001). Moreover, all third trimester measurements were also inversely associated with stunting (odds ratios (95% confidence intervals): Zac= 0.76 (0.64–0.91); Zbp =0.81 (0.67–0.97); Zfl= 0.75(0.64–0.88); Zhc=0.82, (0.69–0.98), p&lt;0.05). The prevalence of SGA in this sample was of 15.9%. The association of third trimester US measurements remained unchanged when the sample was restricted to non‐SGA children, indicating the information provided by prenatal measurements was independent of SGA status.In conclusion, US measures could be useful predictors of child growth through 1 y. Prenatal detection of children at risk of growth faltering can contribute to timely implementation of interventions to promote child growth.Support or Funding InformationFunded by the Mathile Institute for the Advancement of Human Nutrition, the Micronutrient Initiative, and Nestle Foundation.

BackgroundStunting, a form of anthropometric failure, disproportionately affects children in developing countries with a higher burden on children living in poverty. How early life deprivation affects physical growth over various life stages is less well-known.ObjectiveWe investigate the short- and long-run associations between household wealth in early life with physical growth in childhood in four low- and middle-income countries to understand the persistent implications of early life conditions of poverty and resource constraints on physical growth.DesignLongitudinal study of eight cohorts of children in four countries – Ethiopia, India, Peru, and Vietnam (n=10,016) – ages 6 months to 15 years, using data from the Young Lives project, 2002–2009. Physical growth outcomes are standardized height-for-age z-scores (HAZ) and stunting. The key exposure is household wealth measured at baseline using a wealth index, an asset-based indicator. Covariates include child's age and sex, caregiver's educational status, household size, and place of residence.ResultsBaseline wealth index is significantly associated with higher physical growth rates as suggested by higher HAZ and lower odds of stunting. We found these associations in all four countries, for younger and older cohorts and for children who experienced changes in living standards. For the older cohort, despite the timing of the first survey at age 7–8 years, which is beyond the critical period of 1,000 days, there are lasting influences of early poverty, even for those who experienced changes in wealth.ConclusionsHousehold wealth in early life matters for physical growth with conditions of poverty and deprivation influencing growth faltering even beyond the 1,000 days window. The influences of early childhood poverty, so prevalent among children in low- and middle-income countries, must be addressed by policies and programs targeting early life but also focusing on older children experiencing growth faltering.

Biomass smoke exposure and somatic growth among children: The RESPIRE and CRECER prospective cohort studies in rural Guatemala

To study the influence of sociological factors, breast feeding and weaning on aflatoxin exposure in children as well as to determine the effect of aflatoxin exposure on child's growth. A questionnaire, administered to the mothers of forty-six children, obtained information on the child's age, sex, residence, feeding, weaning and general health status. Maternal parity, education and occupation were also collected. Height for age Z-score (HAZ) and weight for age Z-score (WAZ) of children were calculated at the time of recruitment. TLC analysis was performed for aflatoxin B1 level in studied children and their mothers. Aflatoxin B1 was detected in 17 out of 46 (36.96%) of children's serum at a median concentration of 51.61 (30.565-62.795) ppm and in 17 out of 46 (36.96%) of mother's serum at a median concentration of 50 (35.59-84.93) ppm. Aflatoxin B1 level was neither affected by child's age, sex, residence whether rural or urban, maternal age, parity, education nor occupation. Aflatoxin B1 in breastfed patients was significantly lower than in non-breastfed ones (p = 0.034). Weight for age Z-score (WAZ) showed no significant difference between aflatoxin B1 negative and positive cases (p = 0.422) while height for age Z-score (HAZ) was significantly lower in aflatoxin B1 positive compared to negative cases (p = 0.001). A significant positive correlation between aflatoxin B1 in the present cases and their mothers (r = 0.881, p = 0.0001) and a significant negative correlation between aflatoxin B1 in present cases and their height-z-score (HAZ) (r = -0.460, p = 0.001) was detected. Breast feeding results in lower aflatoxin exposure. Also, a strong association between aflatoxin exposure and impaired child's growth exists.

The education system in Peru and many other developing countries faces several challenges, including improving education achievement and increasing education enrollment in high school. It is clear from several indicators that rural students have lower education outcomes than do urban students. In this study we used cross-sectional and longitudinal analysis to determine the relationship between height-for-age z-scores (HAZ), weight-for-age z-scores (WAZ), body-mass index (BMI), and education outcomes. The sample was composed of students from 20 elementary public schools in two rural zones in Peru. The descriptive results show that there was no association between any of the anthropometric variables and achievement (mathematics and reading comprehension) or advancing to high school without repeating a grade. However, BMI was associated with dropping out of school: children with higher BMI in 1998 were more likely to be out of school by 2001. The hierarchical multivariate analysis also showed no relationship between anthropometry and achievement at the individual level, but students with relatively higher HAZ in 1998 were more likely to be drop-outs by 2001. These results contradict prior findings that showed a positive association between anthropometric variables (especially HAZ) and education achievement. The results might be explained by the fact that the study was carried out at very poor sites, at altitudes between 3000 and 3500 meters above sea level. The scarce studies about development in high altitudes suggest that the patterns for height and weight for children and adolescents are different than at sea level. Another possible explanation has to do with the fact that in the contexts studied, children who are perceived as relatively heavier (BMI) or taller (HAZ) might be expected to be out of school and start working (in fact, this was the primary reason given by children for dropping out of school).

Age-stratified path analyses modeled associations between enteric pathogen reservoirs, transmission pathways and height-for-age z-scores (HAZ) to identify determinants of childhood growth in the Kolkata, India site of the Global Enteric Multicenter Study (GEMS). Models tested direct associations of potential pathogen reservoirs with HAZ at 60-day follow-up in separate moderate and severe diarrhea (MSD) case and control cohorts or indirectly when mediated by enteric infections. In the MSD cohort, rotavirus and typical EPEC (tEPEC) infections among children 0-11 months of age and ST-ETEC infections among children 12-23 months of age were associated with lower HAZ. Handwashing after defecating and before cooking reduced impaired growth through reductions in rotavirus and tEPEC infections. Water storage increased rotavirus and ST-ETEC infection risks, resulting in increased impaired growth, but was reduced with reported child feces disposal. The GII norovirus variant was inversely associated with HAZ among children 12-59 months of age in the control cohort. Reported handwashing before the handling of children reduced GII infections and impaired growth. Boiling water and the disposal of children's feces mediated by stored water were positively associated with HAZ. The targeting of pathogen-specific reservoirs and transmission pathways may more effectively improve childhood linear growth in South Asian urban communities.