Thorough training, continuous standardization, and close monitoring of the adherence to measurement procedures during data collection are essential for minimizing random error and bias in multicenter studies. Rigorous anthropometry and data collection protocols were used in the WHO Multicentre Growth Reference Study to ensure high data quality. After the initial training and standardization, study teams participated in standardization sessions every two months for a continuous assessment of the precision and accuracy of their measurements. Once a year the teams were restandardized against the WHO lead anthropometrist, who observed their measurement techniques and retrained any deviating observers. Robust and precise equipment was selected and adapted for field use. The anthropometrists worked in pairs, taking measurements independently, and repeating measurements that exceeded preset maximum allowable differences. Ongoing central and local monitoring identified anthropometrists deviating from standard procedures, and immediate corrective action was taken. The procedures described in this paper are a model for research settings.

An estimated 165 million children are stunted due to the combined effects of poor nutrition, repeated infection and inadequate psychosocial stimulation. The complementary feeding period, generally corresponding to age 6-24 months, represents an important period of sensitivity to stunting with lifelong, possibly irrevocable consequences. Interventions to improve complementary feeding practices or the nutritional quality of complementary foods must take into consideration the contextual as well as proximal determinants of stunting. This review presents a conceptual framework that highlights the role of complementary feeding within the layers of contextual and causal factors that lead to stunted growth and development and the resulting short-and long-term consequences. Contextual factors are organized into the following groups: political economy; health and health care systems; education; society and culture; agriculture and food systems; and water, sanitation and environment. We argue that these community and societal conditions underlie infant and young child feeding practices, which are a central pillar to healthy growth and development, and can serve to either impede or enable progress. Effectiveness studies with a strong process evaluation component are needed to identify transdisciplinary solutions. Programme and policy interventions aimed at preventing stunting should be informed by careful assessment of these factors at all levels.

Objectives: To 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. Design: Secondary 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. Settings: Bangladesh, Dominican Republic and a pooled sample of infants from North America and Northern Europe. Subjects: Respectively 4787, 10 381 and 226 infants and children. Results: Healthy breast-fed infants tracked along the WHO standard's 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%. Conclusions: The 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.

The objective of the Motor Development Study was to describe the acquisition of selected gross motor milestones among affluent children growing up in different cultural settings. This study was conducted in Ghana, India, Norway, Oman, and the United States as part of the longitudinal component of the World Health Organization (WHO) Multicentre Growth Reference Study (MGRS). Infants were followed from the age of four months until they could walk independently. Six milestones that are fundamental to acquiring self-sufficient erect locomotion and are simple to evaluate were assessed: sitting without support, hands-and-knees crawling, standing with assistance, walking with assistance, standing alone, and walking alone. The information was collected by both the children's caregivers and trained MGRS fieldworkers. The caregivers assessed and recorded the dates when the milestones were achieved for the first time according to established criteria. Using standardized procedures, the fieldworkers independently assessed the motor performance of the children and checked parental recording at home visits. To ensure standardized data collection, the sites conducted regular standardization sessions. Data collection and data quality control took place simultaneously. Data verification and cleaning were performed until all queries had been satisfactorily resolved.

Objective: To describe the worldwide implementation of the WHO Child Growth Standards ('WHO standards'). Design: A questionnaire on the adoption of the WHO standards was sent to health authorities. The questions concerned anthropometric indicators adopted, newly introduced indicators, age range, use of sex-specific charts, previously used references, classification system, activities undertaken to roll out the standards and reasons for non-adoption. Setting: Worldwide. Subjects: Two hundred and nineteen countries and territories. Results: By April 2011, 125 countries had adopted the WHO standards, another twenty-five were considering their adoption and thirty had not adopted them. Preference for local references was the main reason for non-adoption. Weight-forage was adopted almost universally, followed by length/height-for-age (104 countries) and weight-for-length/height (eighty-eight countries). Several countries (thirty-six) reported newly introducing BMI-for-age. Most countries opted for sex-specific charts and the Z-score classification. Many redesigned their child health records and updated recommendations on infant feeding, immunization and other health messages. About two-thirds reported incorporating the standards into pre-service training. Other activities ranged from incorporating the standards into computerized information systems, to providing supplies of anthropometric equipment and mobilizing resources for the standards' roll-out. Conclusions: Five years after their release, the WHO standards have been widely scrutinized and implemented. Countries have adopted and harmonized best practices in child growth assessment and established the breast-fed infant as the norm against which to assess compliance with children's right to achieve their full genetic growth potential.