Cutberto Garza

Comparison of the World Health Organization (WHO) Child Growth Standards and the National Center for Health Statistics/WHO international growth reference: implications for child health programmes

OBJECTIVESnTo compare growth patterns and estimates of malnutrition based on the World Health Organization (WHO) Child Growth Standards (the WHO standards) and the National Center for Health Statistics (NCHS)/WHO international growth reference (the NCHS reference), and discuss implications for child health programmes.nnnDESIGNnSecondary analysis of longitudinal data to compare growth patterns (birth to 12 months) and data from two cross-sectional surveys to compare estimates of malnutrition among under-fives.nnnSETTINGSnBangladesh, Dominican Republic and a pooled sample of infants from North America and Northern Europe.nnnSUBJECTSnRespectively 4787, 10 381 and 226 infants and children.nnnRESULTSnHealthy breast-fed infants tracked along the WHO standards weight-for-age mean Z-score while appearing to falter on the NCHS reference from 2 months onwards. Underweight rates increased during the first six months and thereafter decreased when based on the WHO standards. For all age groups stunting rates were higher according to the WHO standards. Wasting and severe wasting were substantially higher during the first half of infancy. Thereafter, the prevalence of severe wasting continued to be 1.5 to 2.5 times that of the NCHS reference. The increase in overweight rates based on the WHO standards varied by age group, with an overall relative increase of 34%.nnnCONCLUSIONSnThe WHO standards provide a better tool to monitor the rapid and changing rate of growth in early infancy. Their adoption will have important implications for child health with respect to the assessment of lactation performance and the adequacy of infant feeding. Population estimates of malnutrition will vary by age, growth indicator and the nutritional status of index populations.

Les standards de croissance de l’Organisation mondiale de la santé pour les nourrissons et les jeunes enfants

The growth pattern of healthy breastfed infants deviates to a significant extent from the NCHS/WHO international reference. In particular, this reference is inadequate because it is based on predominantly formula-fed infants, as are most national growth charts in use today. The WHO multicentre growth reference study (MGRS), aimed at describing the growth of healthy breastfed infants living in good hygiene conditions, was conducted between 1997 and 2003 in 6 countries from diverse geographical regions: Brazil, Ghana, India, Norway, Oman and the United States. The study combined a longitudinal follow-up of 882 infants from birth to 24 months with a cross-sectional component of 6669 children aged 18-71 months. In the longitudinal follow-up study, mothers and newborns were enrolled at birth and visited at home a total of 21 times at weeks 1, 2, 4 and 6; monthly from 2-12 months; and bimonthly in the 2nd year. The study populations lived in socioeconomic conditions favorable to growth. The individual inclusion criteria for the longitudinal component were: no known health or environmental constraints to growth, mothers willing to follow MGRS feeding recommendations (i.e., exclusive or predominant breastfeeding for at least 4 months, introduction of complementary foods by 6 months of age and continued breastfeeding to at least 12 months of age), no maternal smoking before and after delivery, single-term birth and absence of significant morbidity. Term low-birth-weight infants were not excluded. The eligibility criteria for the cross-sectional component were the same as those for the longitudinal component with the exception of infant feeding practices. A minimum of 3 months of any breastfeeding was required for participants in the studys cross-sectional component. Weight-for-age, length/height-for-age, weight-for-length/height and body mass index-for-age percentile and Z-score values were generated for boys and girls aged 0-60 months. The full set of tables and charts is presented on the WHO website (www.who.int/childgrowth/en), together with tools such as software and training materials that facilitate their application. The WHO child growth standards were derived from children who were raised in environments that minimized constraints to growth, such as poor diets and infection. In addition, their mothers followed healthy practices such as breastfeeding their children and not smoking during and after pregnancy. The standards depict normal human growth under optimal environmental conditions and can be used to assess children everywhere, regardless of ethnicity, socioeconomic status and type of feeding. The standards explicitly identify breastfeeding as the biological norm and establish the breastfed child as the normative model for growth and development. They have the potential to significantly strengthen health policies and public support for breastfeeding. The pooled sample from the 6 participating countries allowed the development of a truly international reference that underscores the fact that child populations grow similarly across the worlds major regions when their health and care needs are met. It also provides a tool that is timely and appropriate for the ethnic diversity seen within countries and the evolution toward increasingly multiracial societies in the Americas and Europe as elsewhere in the world. The WHO standards provide a better tool to monitor the rapid and changing rate of growth in early infancy. They also demonstrate that healthy children from around the world who are raised in healthy environments and follow recommended feeding practices have strikingly similar patterns of growth.

A new international growth reference for young children

Growth references for children are among the most widely used instruments in public health and clinical medicine. A comprehensive review by the World Health Organization (WHO) of the use and interpretation of anthropometric data concluded that the present international growth reference for infants does not describe physiologic growth adequately; thus, a new anthropometric reference was recommended for young children from birth to 5 y. The approach taken by the WHO for development of a new reference is guided by the principle that anthropometric reference data must always reflect the functional context of their intended uses and an awareness of the consequences of their application. The new reference will be constructed from data to be collected in a longitudinal study of infants who will be exclusively or predominantly breast-fed for >/=4 mo with continued breast-feeding throughout the first year, and a cross-sectional study of infants and young children aged 18-71 mo. The sample will be drawn from >/=7 diverse geographic sites around the world. The adopted protocol is expected to provide a single international reference that represents the best standard possible of optimal growth for all children <5 y of age. Furthermore, documentation will be sufficient to allow for possible future revision of the reference as substantial new biological information on the growth of infants and young children becomes available.

Bone Mineralization Outcomes in Human Milk-Fed Preterm Infants

ABSTRACTS: We evaluated bone mineralization by single photon absorptiometry at 2 y in a cohort of preterm infants studied since birth. Infants were fed human milk fortified with Ca [to achieve 80 mg/dL (19.96 mmol/L)] and P [40 mg/dL (12.91 mmol/L)] from wk 2 through 8 after birth. After hospital discharge, infants were divided into two groups (HM and F) determined by the timing of the introduction of cow milk-based formula. Mid-radius bone mineral content (BMC) was assessed in 10 infants who were breast-fed (HM) for a minimum of 2 mo after hospital discharge and 11 who were bottle-fed (F). The mean duration of human milk-feeding differed by design between HM and F groups (31 ± 15 versus 11 ± 3 wk, respectively). Although we had observed previously that group F had significantly greater BMC values at 16, 25, and 52 wk compared with values in group HM, we found similarities in BMC values (180 ± 30 mg/cm) between groups at 2 y. The 2-y cohort comprised healthy infants and the groups had similar birth weights, lengths of gestation, and values for weight (10.8 ± 1.1 kg), length (82 ± 2 cm), and bone width (7.8 ± 1.1 mm). Follow-up outcomes at 2 y in preterm infants fed fortified human milk in hospital suggest that if they continue to receive human milk after hospital discharge, radios BMC will “catch-up” to that of similar infants given formula in the posthospitalization period.

Bringing Individuality to Public Health Recommendations

The data generated from the human genome project offers unprecedented opportunities to elucidate the etiology of chronic diseases and developmental anomalies that arise from deleterious genome-diet interactions. Folate metabolism is an attractive system to explore such relationships. Folate is necessary for the synthesis of purine and thymidine deoxyribonucleotides and S-adenosylmethionine, a cofactor required for DNA methylation. Impaired folate metabolism results from primary folate deficiency, alcohol, gastrointestinal disorders that result in malabsorption, single nucleotide polymorphisms, increased folate catabolism and secondary nutrient deficiencies in vitamin B-6, vitamin B-12 and iron arising from a variety of pathologies. Any of these conditions singly or in combination influence DNA synthesis, DNA integrity, allelic-specific gene expression, chromatin structure and DNA mutation rates. Biochemical manifestations of impaired folate metabolism include increased uracil uptake into DNA, altered DNA methylation status and elevated homocysteine and S-adenosylhomocysteine in serum and tissues. These biochemical changes are associated with risk for cancer, cardiovascular disease, neural tube defects and some neuropathies and anemia, although direct causative mechanisms have not been established in all cases. Interactions between folate and the genome are reciprocal; polymorphisms in key genes influence folate nutritional requirements, indicating that dietary folate adequacy likely exerts selective pressure and thereby influences genetic variation. Other studies indicate that exposure to excess folate, perhaps at levels that occur at the upper end of the intake distribution curve, may have unintended consequences in promoting embryo viability. Therefore individualizing folic acid dietary recommendations necessitates a detailed understanding of all genetic and physiological variables that influence the interaction of folate with the genome and their relationship to the disease process.

Post-partum weight change patterns in the WHO Multicentre Growth Reference Study

The interplay of factors that affect post-partum loss or retention of weight gained during pregnancy is not fully understood. The objective of this paper is to describe patterns of weight change in the six sites of the World Health Organization (WHO) Multicentre Growth Reference Study (MGRS) and explore variables that explain variation in weight change within and between sites. Mothers of 1743 breastfed children enrolled in the MGRS had weights measured at days 7, 14, 28 and 42 post-partum, monthly from 2 to 12 months and bimonthly thereafter until 24 months post-partum. Height, maternal age, parity and employment status were recorded and breastfeeding was monitored throughout the follow-up. Weight change patterns varied significantly among sites. Ghanaian and Omani mothers lost little or gained weight post-partum. In Brazil, India, Norway and USA, mothers on average lost weight during the first year followed by stabilization in the second year. Lactation intensity and duration explained little of the variation in weight change patterns. In most sites, obese mothers tended to lose less weight than normal-weight mothers. In Brazil and Oman, primiparous mothers lost about 1u2003kg more than multiparous mothers in the first 6 months. In India and Ghana, multiparous mothers lost about 0.6u2003kg more than primiparas in the second 6 months. Culturally defined mother-care practices probably play a role in weight change patterns among lactating women. This hypothesis should stimulate investigation into gestational weight gain and post-partum losses in different ethnocultural contexts.

Influence of Early Feeding Mode on Body Composition of Infants

To determine the effect of infant feeding mode on body composition, a cross-sectional study was designed in which 10 breast-fed and 10 formula-fed infants were studied at 1 month of age, and another 10 breast-fed and 10 formula-fed infants at 4 months of age. Anthropometric measurements included body weights, lengths, selected diameters, circumferences and skinfold thicknesses. Total body water (TBWO) was measured by 18O dilution. A dose equivalent to 300 mg 18O/kg body weight was administered orally to the infants. Fat-free mass (FFMO) was calculated from TBWO using reference hydration constants of 0.805 and 0.798 at 1 and 4 months, respectively. Body fatO was taken as the difference between weight and FFMO. Total-body electrical conductivity (TOBEC) measurements were used to estimate FFMT and FATT. ANOVA was used to analyze the anthropometric and body composition data using feeding mode and age as grouping factors. Anthropometric measurements did not differ by feeding mode. TBW (kg) and FFM (kg) and body fat (kg) derived from 18O dilution or TOBEC did not differ by feeding mode. TBWO,T (%wt), FFMO,T (%wt), and body fatO,T (%wt) derived from 18O dilution and TOBEC differed significantly between the breast-fed and formula-fed infants at 4 months of age (p < 0.05). Expressed as a percentage of body weight, TBWO and FFMO,T were higher and body fatO,T was lower among the 4-month formula-fed infants.

22nd Marabou Symposium: the changing faces of vitamin D

The classic role of vitamin D has involved its function in calcium metabolism. However, a much broader perspective of the importance of vitamin D is now emerging. Therefore, a new approach is needed based on a combination of molecular biological, physiological, and clinical/epidemiological studies. The remarkable range of the effects of vitamin D relates to our new understanding of both the role of the vitamin D receptor and analyses of what might be considered an optimum vitamin D status in populations exposed to very different diets and levels of sun exposure. Assessing the breadth of the current approaches was the basis of the 22(nd) Marabou Symposium that took place in Stockholm in June 2007.

Complementary feeding and attained linear growth among 6-23-month-old children.

OBJECTIVEnTo examine the association between complementary feeding indicators and attained linear growth at 6-23 months.nnnDESIGNnSecondary analysis of Phase V Demographic and Health Surveys data (2003-2008). Country-specific ANOVA models were used to estimate effects of three complementary feeding indicators (minimum meal frequency, minimum dietary diversity and minimum adequate diet) on length-for-age, adjusted for covariates and interactions of interest.nnnSETTINGnTwenty-one countries (four Asian, twelve African, four from the Americas and one European).nnnSUBJECTSnSample sizes ranging from 608 to 13 676.nnnRESULTSnLess than half the countries met minimum meal frequency and minimum dietary diversity, and only Peru had a majority of the sample receiving a minimum adequate diet. Minimum dietary diversity was the indicator most consistently associated with attained length, having significant positive effect estimates (ranging from 0·16 to 1·40 for length-for-age Z-score) in twelve out of twenty-one countries. Length-for-age declined with age in all countries, and the greatest declines in its Z-score were seen in countries (Niger, -1·9; Mali, -1·6; Democratic Republic of Congo, -1·4; Ethiopia, -1·3) where dietary diversity was persistently low or increased very little with age.nnnCONCLUSIONSnThere is growing recognition that poor complementary feeding contributes to the characteristic negative growth trends observed in developing countries and therefore needs focused attention and its own tailored interventions. Dietary diversity has the potential to improve linear growth. Using four food groups to define minimum dietary diversity appears to capture enough information in a simplified, standard format for multi-country comparisons of the quality of complementary diets.

Parental height and child growth from birth to 2 years in the WHO Multicentre Growth Reference Study.

Linear growth from birth to 2 years of children enrolled in the World Health Organization Multicentre Growth Reference Study was similar despite substantial parental height differences among the six study sites. Within-site variability in child length attributable to parental height was estimated by repeated measures analysis of variance using generalized linear models. This approach was also used to examine relationships among selected traits (e.g. breastfeeding duration and child morbidity) and linear growth between 6 and 24 months of age. Differences in intergenerational adult heights were evaluated within sites by comparing mid-parental heights (average of the mothers and fathers heights) to the childrens predicted adult height. Mid-parental height consistently accounted for greater proportions of observed variability in attained child length than did either paternal or maternal height alone. The proportion of variability explained by mid-parental height ranged from 11% in Ghana to 21% in India. The average proportion of between-child variability accounted for by mid-parental height was 16% and the analogous within-child estimate was 6%. In the Norwegian and US samples, no significant differences were observed between mid-parental and childrens predicted adult heights. For the other sites, predicted adult heights exceeded mid-parental heights by 6.2-7.8u2009cm. To the extent that adult height is predicted by height at age 2 years, these results support the expectation that significant community-wide advances in stature are attainable within one generation when care and nutrition approximate international recommendations, notwithstanding adverse conditions likely experienced by the previous generation.