DECEMBER 13, 2013
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About the Authors:
Jef Leroy is a Research Fellow in IFPRI’s Poverty, Health, and Nutrition Division. At IFPRI, he studies the impact of two large-scale integrated food and nutrition programs in Burundi and Guatemala on maternal and child nutrition and health. Before joining IFPRI in 2009, he was a research associate at the Center for Evaluation Research and Surveys at the National Institute of Public Health in Mexico. He has worked on the impact evaluation of large-scale programs, including the impact of the urban and rural Oportunidades programs on child nutrition and health, and the impact of the Programa de Apoyo Alimentario (an in-kind transfer program) on household food consumption and women’s weight. He has also conducted research on child mortality. Jef has a PhD in International Nutrition (Cornell University) and a MSc in Agricultural and Applied Biological Sciences (Ghent University, Belgium).
Marie Ruel was appointed Division Director of IFPRI’s Poverty, Health and Nutrition Division in 2004. From 1996 until her current appointment, she served as (Senior) Research Fellow in that division. Prior to IFPRI, she was head of the Nutrition and Health Division at the Institute of Nutrition of Central America and Panama/Pan American Health Organization (INCAP/PAHO) in Guatemala. Dr. Ruel received her PhD in International Nutrition from Cornell University and her Masters in Health Sciences from Laval University in Canada. Dr. Ruel has worked for more than 25 years on issues related to policies and programs to alleviate poverty and child malnutrition in developing countries. She has published extensively on topics such as maternal and child nutrition, agriculture and food-based strategies to improve diet quality and micronutrient nutrition, urban livelihoods, food security and nutrition, the development and validation of indicators of child feeding and care practices, and program evaluation. Her current research focuses on the evaluation and strengthening of a wide range of integrated, multi-sectoral development programs in the area of social protection and agriculture and at building the evidence on their role in reducing maternal and child malnutrition globally. She has served on various international expert committees, such as the National Academy of Sciences, the International Zinc in Nutrition Consultative Group, the Society for International Nutrition Research, and the Micronutrient Forum. She recently led the development of a large CGIAR program on Agriculture for Improved Nutrition and Health, and is currently contributing to its successful implementation.
Jean-Pierre Habicht is a Graduate Professor of Epidemiology in the Division of Nutritional Sciences at Cornell University. Dr. Habicht obtained medical training in Switzerland, further pediatric training in the US, a PhD in Nutritional Biochemistry from MIT, and public health training (MPH) from Harvard. He worked in Guatemala for the Institute of Nutrition of Central America as a World Health Organization medical officer in charge of primary health care and epidemiological studies, and then worked for the US National Center for Health Statistics on nutritional surveillance. He came to Cornell University in 1977 to develop a program of research and study in nutritional epidemiology that included the biological and social determinants of malnutrition in developing countries with emphasis on program development and evaluation to prevent and alleviate malnutrition in mothers and children. Much of his research has focused on elucidating the nutritional determinants of health, performance, and survival in mothers and in children from conception through childhood. He has developed and tested nutritional surveillance systems that can trigger interventions to prevent famines, and more importantly, to help design policy to improve nutritional status. His expertise is also pertinent to US domestic nutrition and health. These interests are developed in retirement by presentations; mentoring; participating in research at Cornell, at the International Food Policy Research Institute, at the Mexican National Institute of Health, and the World Health Organization (WHO); by participating in conferences; and by serving on policy venues such as the WHO Expert Committee on Nutrition and the Board of Helen Keller International, an international non-governmental humanitarian organization.
What’s Up with Catch-up? On the Meaningful Measurement of Child Growth Retardation
Linear growth retardation in children remains an important global problem, with an estimated 165 million children under five being stunted (Black et al. 2013). Growth retardation in young children is strongly associated with delays in cognitive development, lower school achievement, lower earnings and a higher probability of non-communicable diseases at adulthood. Given the importance of these functional correlates for development, the possibility that linear growth retardation might be (even if only partially) reversed—often referred to as catch-up growth—has been studied extensively. Evidence from studies conducted in past decades showed little or no catch-up growth in children who remained in the same deprived settings in which growth retardation had occurred in the first place (Martorell et al. 1994).
A number of recent studies, however, claim to have found evidence of catch-up growth after 2 years of age in children exposed to standard of care practices typical of developing country contexts (Prentice et al. 2013). These recent claims, however, are based on the use of height-for-age z-scores as the measure of linear growth.
We argue in this paper that using improvements in z-scores with age to define population level catch-up growth leads to the wrong conclusions. Our first objective is to show mathematically that the use of anthropometric z-scores induces growth patterns that are wrongly interpreted as catch-up growth. We propose the use of the absolute growth deficit as the preferred measure of linear growth retardation. Second, we present data from national surveys from developing countries to demonstrate the different patterns that result if absolute deficit is used to measure mean population growth instead of z-scores as is current practice. We conclude with a discussion of the major policy implications of our findings for the measurement and reporting of growth patterns in young children.
Black, R., C. Victora, and S. Walker. 2013. Maternal and child undernutrition and overweight in low-income and middle-income countries. The Lancet (published online June 6, 2013).
Martorell, R., L. K. Khan, and D. G. Schroeder. 1994. Reversibility of stunting: epidemiological findings in children from developing countries. European Journal of Clinical Nutrition 45(Suppl 1): S45–S57.
Prentice, A. M., K. A. Ward, G. R. Goldberg, L. M. Jarjou, S. E. Moore, A. J. Fulford, and A. Prentice. 2013. Critical windows for nutritional interventions against stunting. American Journal of Clinical Nutrition 97(5): 911–8.