National, regional, and global estimates of low birthweight in 2020, with trends from 2000: a systematic analysis.

BACKGROUND: Low birthweight (LBW; <2500 g) is an important predictor of health outcomes throughout the life course. We aimed to update country, regional, and global estimates of LBW prevalence for 2020, with trends from 2000, to assess progress towards global targets to reduce LBW by 30% by 2030. METHODS: For this systematic analysis, we searched population-based, nationally representative data on LBW from Jan 1, 2000, to Dec 31, 2020. Using 2042 administrative and survey datapoints from 158 countries and areas, we developed a Bayesian hierarchical regression model incorporating country-specific intercepts, time-varying covariates, non-linear time trends, and bias adjustments based on data quality. We also provided novel estimates by birthweight subgroups. FINDINGS: An estimated 19·8 million (95% credible interval 18·4-21·7 million) or 14·7% (13·7-16·1) of liveborn newborns were LBW worldwide in 2020, compared with 22·1 million (20·7-23·9 million) and 16·6% (15·5-17·9) in 2000-an absolute reduction of 1·9 percentage points between 2000 and 2020. Using 2012 as the baseline, as this is when the Global Nutrition Target began, the estimated average annual rate of reduction from 2012 to 2020 was 0·3% worldwide, 0·85% in southern Asia, and 0·59% in sub-Saharan Africa. Nearly three-quarters of LBW births in 2020 occurred in these two regions: of 19 833 900 estimated LBW births worldwide, 8 817 000 (44·5%) were in southern Asia and 5 381 300 (27·1%) were in sub-Saharan Africa. Of 945 300 estimated LBW births in northern America, Australia and New Zealand, central Asia, and Europe, approximately 35·0% (323 700) weighed less than 2000 g: 5·8% (95% CI 5·2-6·4; 54 800 [95% CI 49 400-60 800]) weighed less than 1000 g, 9·0% (8·7-9·4; 85 400 [82 000-88 900]) weighed between 1000 g and 1499 g, and 19·4% (19·0-19·8; 183 500 [180 000-187 000]) weighed between 1500 g and 1999 g. INTERPRETATION: Insufficient progress has occurred over the past two decades to meet the Global Nutrition Target of a 30% reduction in LBW between 2012 and 2030. Accelerating progress requires investments throughout the lifecycle focused on primary prevention, especially for adolescent girls and women living in the most affected countries. With increasing numbers of births in facilities and advancing electronic information systems, improvements in the quality and availability of administrative LBW data are also achievable. FUNDING: The Children's Investment Fund Foundation; the UNDP-UNFPA-UNICEF-WHO World Bank Special Programme of Research, Development and Research Training in Human Reproduction; and the Bill & Melinda Gates Foundation.

Small babies, big risks: global estimates of prevalence and mortality for vulnerable newborns to accelerate change and improve counting.

Small newborns are vulnerable to mortality and lifelong loss of human capital. Measures of vulnerability previously focused on liveborn low-birthweight (LBW) babies, yet LBW reduction targets are off-track. There are two pathways to LBW, preterm birth and fetal growth restriction (FGR), with the FGR pathway resulting in the baby being small for gestational age (SGA). Data on LBW babies are available from 158 (81%) of 194 WHO member states and the occupied Palestinian territory, including east Jerusalem, with 113 (58%) having national administrative data, whereas data on preterm births are available from 103 (53%) of 195 countries and areas, with only 64 (33%) providing national administrative data. National administrative data on SGA are available for only eight countries. Global estimates for 2020 suggest 13·4 million livebirths were preterm, with rates over the past decade remaining static, and 23·4 million were SGA. In this Series paper, we estimated prevalence in 2020 for three mutually exclusive types of small vulnerable newborns (SVNs; preterm non-SGA, term SGA, and preterm SGA) using individual-level data (2010-20) from 23 national datasets (∼110 million livebirths) and 31 studies in 18 countries (∼0·4 million livebirths). We found 11·9 million (50% credible interval [Crl] 9·1-12·2 million; 8·8%, 50% Crl 6·8-9·0%) of global livebirths were preterm non-SGA, 21·9 million (50% Crl 20·1-25·5 million; 16·3%, 14·9-18·9%) were term SGA, and 1·5 million (50% Crl 1·2-4·2 million; 1·1%, 50% Crl 0·9-3·1%) were preterm SGA. Over half (55·3%) of the 2·4 million neonatal deaths worldwide in 2020 were attributed to one of the SVN types, of which 73·4% were preterm and the remainder were term SGA. Analyses from 12 of the 23 countries with national data (0·6 million stillbirths at ≥22 weeks gestation) showed around 74% of stillbirths were preterm, including 16·0% preterm SGA and approximately one-fifth of term stillbirths were SGA. There are an estimated 1·9 million stillbirths per year associated with similar vulnerability pathways; hence integrating stillbirths to burden assessments and relevant indicators is crucial. Data can be improved by counting, weighing, and assessing the gestational age of every newborn, whether liveborn or stillborn, and classifying small newborns by the three vulnerability types. The use of these more specific types could accelerate prevention and help target care for the most vulnerable babies.

Data gaps towards health development goals, 47 low- and middle-income countries.

OBJECTIVE: To assess the availability and gaps in data for measuring progress towards health-related sustainable development goals and other targets in selected low- and middle-income countries. METHODS: We used 14 international population surveys to evaluate the health data systems in the 47 least developed countries over the years 2015-2020. We reviewed the survey instruments to determine whether they contained tools that could be used to measure 46 health-related indicators defined by the World Health Organization. We recorded the number of countries with data available on the indicators from these surveys. FINDINGS: Twenty-seven indicators were measurable by the surveys we identified. The two health emergency indicators were not measurable by current surveys. The percentage of countries that used surveys to collect data over 2015-2020 were lowest for tuberculosis (2/47; 4.3%), hepatitis B (3/47; 6.4%), human immunodeficiency virus (11/47; 23.4%), child development status and child abuse (both 13/47; 27.7%), compared with safe drinking water (37/47; 78.7%) and births attended by skilled health personnel (36/47; 76.6%). Nineteen countries collected data on 21 or more indicators over 2015-2020 while nine collected data on no indicators; over 2018-2020 these numbers reduced to six and 20, respectively. CONCLUSION: Examining selected international surveys provided a quick summary of health data available in the 47 least developed countries. We found major gaps in health data due to long survey cycles and lack of appropriate survey instruments. Novel indicators and survey instruments would be needed to track the fast-changing situation of health emergencies.

Estimating Childhood Stunting and Overweight Trends in the European Region from Sparse Longitudinal Data.

BACKGROUND: Monitoring countries' progress toward the achievement of their nutrition targets is an important task, but data sparsity makes monitoring trends challenging. Childhood stunting and overweight data in the European region over the last 30 y have had low coverage and frequency, with most data only covering a portion of the complete age interval of 0-59 mo. OBJECTIVES: We implemented a statistical method to extract useful information on child malnutrition trends from sparse longitudinal data for these indicators. METHODS: Heteroscedastic penalized longitudinal mixed models were used to accommodate data sparsity and predict region-wide, country-level trends over time. We leveraged prevalence estimates stratified by sex and partial age intervals (i.e., intervals that do not cover the complete 0-59 mo), which expanded the available data (for stunting: from 84 sources and 428 prevalence estimates to 99 sources and 1786 estimates), improving the robustness of our analysis. RESULTS: Results indicated a generally decreasing trend in stunting and a stable, slightly diminishing rate for overweight, with large differences in trends between low- and middle-income countries compared with high-income countries. No differences were found between age groups and between sexes. Cross-validation results indicated that both stunting and overweight models were robust in estimating the indicators for our data (root mean squared error: 0.061 and 0.056; median absolute deviation: 0.045 and 0.042; for stunting and overweight, respectively). CONCLUSIONS: These statistical methods can provide useful and robust information on child malnutrition trends over time, even when data are sparse.

Prediction intervals for penalized longitudinal models with multisource summary measures: An application to childhood malnutrition.

In many global health analyses, it is of interest to examine countries' progress using indicators of socio-economic conditions based on national surveys from varying sources. This results in longitudinal data where heteroscedastic summary measures, rather than individual level data, are available. Administration of national surveys can be sporadic, resulting in sparse data measurements for some countries. Furthermore, the trend of the indicators over time is usually nonlinear and varies by country. It is of interest to track the current level of indicators to determine if countries are meeting certain thresholds, such as those indicated in the United Nations Sustainable Development Goals. In addition, estimation of confidence and prediction intervals are vital to determine true changes in prevalence and where data is low in quantity and/or quality. In this article, we use heteroscedastic penalized longitudinal models with survey summary data to estimate yearly prevalence of malnutrition quantities. We develop and compare methods to estimate confidence and prediction intervals using asymptotic and parametric bootstrap techniques. The intervals can incorporate data from multiple sources or other general data-smoothing steps. The methods are applied to African countries in the UNICEF-WHO-The World Bank joint child malnutrition data set. The properties of the intervals are demonstrated through simulation studies and cross-validation of real data.

Prevalence thresholds for wasting, overweight and stunting in children under 5 years.

OBJECTIVE: Prevalence ranges to classify levels of wasting and stunting have been used since the 1990s for global monitoring of malnutrition. Recent developments prompted a re-examination of existing ranges and development of new ones for childhood overweight. The present paper reports from the WHO-UNICEF Technical Expert Advisory Group on Nutrition Monitoring. DESIGN: Thresholds were developed in relation to sd of the normative WHO Child Growth Standards. The international definition of 'normal' (2 sd below/above the WHO standards median) defines the first threshold, which includes 2·3 % of the area under the normalized distribution. Multipliers of this 'very low' level (rounded to 2·5 %) set the basis to establish subsequent thresholds. Country groupings using the thresholds were produced using the most recent set of national surveys. SETTING: One hundred and thirty-four countries. SUBJECTS: Children under 5 years. RESULTS: For wasting and overweight, thresholds are: 'very low' (≈6 times 2·5 %). For stunting, thresholds are: 'very low' (≈12 times 2·5 %). CONCLUSIONS: The proposed thresholds minimize changes and keep coherence across anthropometric indicators. They can be used for descriptive purposes to map countries according to severity levels; by donors and global actors to identify priority countries for action; and by governments to trigger action and target programmes aimed at achieving 'low' or 'very low' levels. Harmonized terminology will help avoid confusion and promote appropriate interventions.

Successive 1-Month Weight Increments in Infancy Can Be Used to Screen for Faltering Linear Growth.

BACKGROUND: Linear growth faltering in the first 2 y contributes greatly to a high stunting burden, and prevention is hampered by the limited capacity in primary health care for timely screening and intervention. OBJECTIVE: This study aimed to determine an approach to predicting long-term stunting from consecutive 1-mo weight increments in the first year of life. METHODS: By using the reference sample of the WHO velocity standards, the analysis explored patterns of consecutive monthly weight increments among healthy infants. Four candidate screening thresholds of successive increments that could predict stunting were considered, and one was selected for further testing. The selected threshold was applied in a cohort of Bangladeshi infants to assess its predictive value for stunting at ages 12 and 24 mo. RESULTS: Between birth and age 12 mo, 72.6% of infants in the WHO sample tracked within 1 SD of their weight and length. The selected screening criterion ("event") was 2 consecutive monthly increments below the 15th percentile. Bangladeshi infants were born relatively small and, on average, tracked downward from approximately age 6 to <24 mo (51% stunted). The population-attributable risk of stunting associated with the event was 14% at 12 mo and 9% at 24 mo. Assuming the screening strategy is effective, the estimated preventable proportion in the group who experienced the event would be 34% at 12 mo and 24% at 24 mo. CONCLUSIONS: This analysis offers an approach for frontline workers to identify children at risk of stunting, allowing for timely initiation of preventive measures. It opens avenues for further investigation into evidence-informed application of the WHO growth velocity standards.

The Global Nutrition Report 2014: actions and accountability to accelerate the world's progress on nutrition.

In 2013, the Nutrition for Growth Summit called for a Global Nutrition Report (GNR) to strengthen accountability in nutrition so that progress in reducing malnutrition could be accelerated. This article summarizes the results of the first GNR. By focusing on undernutrition and overweight, the GNR puts malnutrition in a new light. Nearly every country in the world is affected by malnutrition, and multiple malnutrition burdens are the "new normal." Unfortunately, the world is off track to meet the 2025 World Health Assembly (WHA) targets for nutrition. Many countries are, however, making good progress on WHA indicators, providing inspiration and guidance for others. Beyond the WHA goals, nutrition needs to be more strongly represented in the Sustainable Development Goal (SDG) framework. At present, it is only explicitly mentioned in 1 of 169 SDG targets despite the many contributions improved nutritional status will make to their attainment. To achieve improvements in nutrition status, it is vital to scale up nutrition programs. We identify bottlenecks in the scale-up of nutrition-specific and nutrition-sensitive approaches and highlight actions to accelerate coverage and reach. Holding stakeholders to account for delivery on nutrition actions requires a well-functioning accountability infrastructure, which is lacking in nutrition. New accountability mechanisms need piloting and evaluation, financial resource flows to nutrition need to be made explicit, nutrition spending targets should be established, and some key data gaps need to be filled. For example, many UN member states cannot report on their WHA progress and those that can often rely on data >5 y old. The world can accelerate malnutrition reduction substantially, but this will require stronger accountability mechanisms to hold all stakeholders to account.

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

OBJECTIVE: To examine the association between complementary feeding indicators and attained linear growth at 6-23 months. DESIGN: Secondary 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. SETTING: Twenty-one countries (four Asian, twelve African, four from the Americas and one European). SUBJECTS: Sample sizes ranging from 608 to 13 676. RESULTS: Less 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. CONCLUSIONS: There 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.

Should a single growth standard be used to judge the nutritional status of children under age 5 y globally? Debate consensus.

The participants in this debate agreed that: 1) target-based advocacy is required for ensuring countries' engagement and political commitments toward reducing child malnutrition, and the tools used for monitoring progress should be accurate and pose no risk of harmful consequences; and 2) physical growth is not the only dimension of nutritional status to be monitored in clinical and public health practice; anthropometry is thus only one of the diagnostic indicators of nutritional status. Key disagreements included methodological approaches for developing a single growth standard to evaluate nutritional status globally; the relative utility of universal and contextual growth standards for clinical practice and public health; the balance of benefits, harms, and acceptability among stakeholders; and their use as a screening or a definitive tool in individual and public health nutrition. Noteworthy agreements for research priorities included comparison of benefits and harms of using universal compared with contextual growth standards/references and different stakeholders' perception of expectations from and utility of growth standards.

Should a single growth standard be used to judge the nutritional status of children under age 5 years globally: Yes.

Childhood nutritional status serves as a lens through which nations and communities identify missed opportunities to improve health and wellbeing across the life cycle, as well as economic development and other related sectors. Countries have committed to the global nutrition targets endorsed by the World Health Assembly in 2012, which were included in the Sustainable Development Goals framework under the target to end all forms of malnutrition by 2030. The child malnutrition indicators for tracking countries' progress toward the agreed-upon targets are based on standard definitions of nutritional status against the widely adopted and used World Health Organization (WHO) Child Growth Standards. The standards were based on a sample of healthy breastfed infants and young children from diverse ethnic backgrounds and cultural settings as part of the WHO Multicentre Growth Reference Study. The WHO Child Growth Standards developed represent the best description of physiological growth for children aged <5 y. The standards depict normal early childhood growth under optimal environmental conditions and can be used to assess children everywhere, regardless of ethnicity, socioeconomic status, and type of feeding.

Should a single growth standard be used to judge the nutritional status of children under age 5 years globally? No.

Universal growth standards for under-five children, given the worldwide variation in healthy growth and several determinants of anthropometry, are imprecise measures of nutritional status, particularly when used cross-sectionally. In constructing the global-use WHO growth standard, linear growth differences between contributing sites and pooled mean were >0.2 SD in 37% of observations. Systematic reviews confirm even greater variability, notably amplified for weight-for-age and head-circumference-for-age metrics. Unsurprisingly, developed nations had higher, and LMICs lower, growth dimensions. Contextual growth references predict neonatal morbidities, pathological short stature, macrocephaly, cardiometabolic risk factors, and adult noncommunicable diseases better than the WHO standards. Child body composition also varies contextually, with greater adiposity despite comparable weights in South Asian populations. Thus, contextual references, though not the perfect solution, are better suited for everyday practice and nutrition policy. Growth standards should only be used as a screening for clinical judgments aided by precise biomarkers.

Correction: Leppäniemi et al. Nutrition Profile for Countries of the Eastern Mediterranean Region with Different Income Levels: An Analytical Review. Children 2023, 10, 236.

In the original publication [...].

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 mother's and father's heights) to the children's 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 children's predicted adult heights. For the other sites, predicted adult heights exceeded mid-parental heights by 6.2-7.8 cm. 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.

The World Health Organization's global target for reducing childhood stunting by 2025: rationale and proposed actions.

In 2012, the World Health Organization adopted a resolution on maternal, infant and young child nutrition that included a global target to reduce by 40% the number of stunted under-five children by 2025. The target was based on analyses of time series data from 148 countries and national success stories in tackling undernutrition. The global target translates to a 3.9% reduction per year and implies decreasing the number of stunted children from 171 million in 2010 to about 100 million in 2025. However, at current rates of progress, there will be 127 million stunted children by 2025, that is, 27 million more than the target or a reduction of only 26%. The translation of the global target into national targets needs to consider nutrition profiles, risk factor trends, demographic changes, experience with developing and implementing nutrition policies, and health system development. This paper presents a methodology to set individual country targets, without precluding the use of others. Any method applied will be influenced by country-specific population growth rates. A key question is what countries should do to meet the target. Nutrition interventions alone are almost certainly insufficient, hence the importance of ongoing efforts to foster nutrition-sensitive development and encourage development of evidence-based, multisectoral plans to address stunting at national scale, combining direct nutrition interventions with strategies concerning health, family planning, water and sanitation, and other factors that affect the risk of stunting. In addition, an accountability framework needs to be developed and surveillance systems strengthened to monitor the achievement of commitments and targets.

Nutrition Profile for Countries of the Eastern Mediterranean Region with Different Income Levels: An Analytical Review.

The World Health Organization's (WHO) Eastern Mediterranean Region (EMR) is suffering from a double burden of malnutrition in which undernutrition coexists with rising rates of overweight and obesity. Although the countries of the EMR vary greatly in terms of income level, living conditions and health challenges, the nutrition status is often discussed only by using either regional or country-specific estimates. This analytical review studies the nutrition situation of the EMR during the past 20 years by dividing the region into four groups based on their income level-the low-income group (Afghanistan, Somalia, Sudan, Syria, and Yemen), the lower-middle-income group (Djibouti, Egypt, Iran, Morocco, Pakistan, Palestine, and Tunisia), the upper-middle-income group (Iraq, Jordan, Lebanon, and Libya) and the high-income group (Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and United Arab Emirates)-and by comparing and describing the estimates of the most important nutrition indicators, including stunting, wasting, overweight, obesity, anaemia, and early initiation and exclusive breastfeeding. The findings reveal that the trends of stunting and wasting were decreasing in all EMR income groups, while the percentages of overweight and obesity predominantly increased in all age groups across the income groups, with the only exception in the low-income group where a decreasing trend among children under five years existed. The income level was directly associated with the prevalence rates of overweight and obesity among other age groups except children under five, while an inverse association was observed regarding stunting and anaemia. Upper-middle-income country group showed the highest prevalence rate of overweight among children under five. Most countries of the EMR revealed below-desired rates of early initiation and exclusive breastfeeding. Changes in dietary patterns, nutrition transition, global and local crises, and nutrition policies are among the major explanatory factors for the findings. The scarcity of updated data remains a challenge in the region. Countries need support in filling the data gaps and implementing recommended policies and programmes to address the double burden of malnutrition.

Prevalence and trends of stunting among pre-school children, 1990-2020.

OBJECTIVE: To quantify the prevalence and trends of stunting among children using the WHO growth standards. DESIGN: Five hundred and seventy-six nationally representative surveys, including anthropometric data, were analysed. Stunting was defined as the proportion of children below -2sd from the WHO length- or height-for-age standards median. Linear mixed-effects modelling was used to estimate rates and numbers of affected children from 1990 to 2010, and projections to 2020. SETTING: One hundred and forty-eight developed and developing countries. SUBJECTS: Boys and girls from birth to 60 months. RESULTS: In 2010, it is estimated that 171 million children (167 million in developing countries) were stunted. Globally, childhood stunting decreased from 39·7 (95 % CI 38·1, 41·4) % in 1990 to 26·7 (95 % CI 24·8, 28·7) % in 2010. This trend is expected to reach 21·8 (95 % CI 19·8, 23·8) %, or 142 million, in 2020. While in Africa stunting has stagnated since 1990 at about 40 % and little improvement is anticipated, Asia showed a dramatic decrease from 49 % in 1990 to 28 % in 2010, nearly halving the number of stunted children from 190 million to 100 million. It is anticipated that this trend will continue and that in 2020 Asia and Africa will have similar numbers of stunted children (68 million and 64 million, respectively). Rates are much lower (14 % or 7 million in 2010) in Latin America. CONCLUSIONS: Despite an overall decrease in developing countries, stunting remains a major public health problem in many of them. The data summarize progress achieved in the last two decades and help identify regions needing effective interventions.

Worldwide implementation of the WHO Child Growth Standards.

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-for-age 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.

Study protocol for UNICEF and WHO estimates of global, regional, and national low birthweight prevalence for 2000 to 2020.

Background Reducing low birthweight (LBW, weight at birth less than 2,500g) prevalence by at least 30% between 2012 and 2025 is a target endorsed by the World Health Assembly that can contribute to achieving Sustainable Development Goal 2 (Zero Hunger) by 2030. The 2019 LBW estimates indicated a global prevalence of 14.6% (20.5 million newborns) in 2015. We aim to develop updated LBW estimates at global, regional, and national levels for up to 202 countries for the period of 2000 to 2020. Methods Two types of sources for LBW data will be sought: national administrative data and population-based surveys. Administrative data will be searched for countries with a facility birth rate ≥80% and included when birthweight data account for ≥80% of UN estimated live births for that country and year. Surveys with birthweight data published since release of the 2019 edition of the LBW estimates will be adjusted using the standard methodology applied for the previous estimates. Risk of bias assessments will be undertaken. Covariates will be selected based on a conceptual framework of plausible associations with LBW, covariate time-series data quality, collinearity between covariates and correlations with LBW. National LBW prevalence will be estimated using a Bayesian multilevel-mixed regression model, then aggregated to derive regional and global estimates through population-weighted averages. Conclusion Whilst availability of LBW data has increased, especially with more facility births, gaps remain in the quantity and quality of data, particularly in low-and middle-income countries. Challenges include high percentages of missing data, lack of adherence to reporting standards, inaccurate measurement, and data heaping. Updated LBW estimates are important to highlight the global burden of LBW, track progress towards nutrition targets, and inform investments in programmes. Reliable, nationally representative data are key, alongside investments to improve the measurement and recording of an accurate birthweight for every baby.

National, regional, and global estimates of anaemia by severity in women and children for 2000-19: a pooled analysis of population-representative data.

BACKGROUND: Anaemia causes health and economic harms. The prevalence of anaemia in women aged 15-49 years, by pregnancy status, is indicator 2.2.3 of the UN Sustainable Development Goals, and the aim of halving the anaemia prevalence in women of reproductive age by 2030 is an extension of the 2025 global nutrition targets endorsed by the World Health Assembly (WHA). We aimed to estimate the prevalence of anaemia by severity for children aged 6-59 months, non-pregnant women aged 15-49 years, and pregnant women aged 15-49 years in 197 countries and territories and globally for the period 2000-19. METHODS: For this pooled analysis of population-representative data, we collated 489 data sources on haemoglobin distribution in children and women from 133 countries, including 4·5 million haemoglobin measurements. Our data sources comprised health examination, nutrition, and household surveys, accessed as anonymised individual records or as summary statistics such as mean haemoglobin and anaemia prevalence. We used a Bayesian hierarchical mixture model to estimate haemoglobin distributions in each population and country-year. This model allowed for coherent estimation of mean haemoglobin and prevalence of anaemia by severity. FINDINGS: Globally, in 2019, 40% (95% uncertainty interval [UI] 36-44) of children aged 6-59 months were anaemic, compared to 48% (45-51) in 2000. Globally, the prevalence of anaemia in non-pregnant women aged 15-49 years changed little between 2000 and 2019, from 31% (95% UI 28-34) to 30% (27-33), while in pregnant women aged 15-49 years it decreased from 41% (39-43) to 36% (34-39). In 2019, the prevalence of anaemia in children aged 6-59 months exceeded 70% in 11 countries and exceeded 50% in all women aged 15-49 years in ten countries. Globally in all populations and in most countries and regions, the prevalence of mild anaemia changed little, while moderate and severe anaemia declined in most populations and geographical locations, indicating a shift towards mild anaemia. INTERPRETATION: Globally, regionally, and in nearly all countries, progress on anaemia in women aged 15-49 years is insufficient to meet the WHA global nutrition target to halve anaemia prevalence by 2030, and the prevalence of anaemia in children also remains high. A better understanding of the context-specific causes of anaemia and quality implementation of effective multisectoral actions to address these causes are needed. FUNDING: USAID, US Centers for Disease Control and Prevention, and Bill & Melinda Gates Foundation.