Modelling growth trajectories of children : a longitudinal analysis of individual and household effects on children's nutritional status in rural Pakistan
This thesis explores the pathways through which individual and household factors are associated with temporal changes in child nutritional status. In this study the concept of nutrition deprivation is used in two ways: firstly as indicated by the child's anthropometric measures, and secondly in terms of food consumption. The thesis also explores how nutritional deprivation is linked with economic deprivation. The main objectives of the study are: to examine the physical growth trajectories of children, to investigate the household's economic and nutritional (food) deprivations, to explore the determinants of child malnutrition, and finally to investigate the relationship between temporal changes in the poverty status of households and temporal changes in child nutritional status. The study uses the Pakistan Panel Data collected by the International Food Policy Research Institute (IFPRI) from 1986-89, covering four rural districts of Pakistan. The study employs a comprehensive child health framework to establish the mechanism of child nutritional status by linking the various factors at child, household and community levels. This framework specifies poverty as the root cause of malnutrition. The basic need absolute poverty approach is used to work out the incidence and the dynamic nature of poverty. Various statistical modelling techniques for analysing the longitudinal data are used in this study. For example, to study the height and weight growth traectories of children a growth curve modelling technique is employed, and to study the determinants of child malnutrition a three-level hierarchical linear model for longitudinal data is used. The predicted average growth velocities indicate a slower growth during first year of child's life in comparison with the usual growth velocities amongst the normal children. However, in a particular cohort of children some evidence of growth acceleration is found during the third year of a child's life after a growth deceleration during the second year. Child level factors, such as breastfeeding and the incidence of diarrhoea and morbidity, are found to explain most of the variability in child nutritional status. The results reveal dissimilarities in nutritional status between children in a household. The results also indicate associations between poverty and stunting while chronic poverty is found to be associated with wasting. The results indicate that caloric and protein consumption amongst the study households was notably high. However, food consumption patterns mostly revolve around the staple food, and even in the top expenditure quintile this pattern remains persistent.