Worldwide, malnutrition is said to be the leading cause of about half of all deaths occurring in children 7 and that Protein-Energy malnutrition is the most prevalent form in the developing countries with the highest incidence in the under-five children 8. Malnutrition is the most significant risk factor for global burden of diseases causing approximately 300,000 deaths per year directly and indirectly accountable for more than half of the deaths occurring in children in the developing countries 9;10. It has been estimated that more than one-quarter of all under-five children in the developing countries are underweight and this accounts for about 143 million children that are underweight in these countries 11. Almost three-quarters of these 143 million underweight children live in just ten countries 11. In addition, more than one-quarter of the under-five children are underweight in Sub-Saharan Africa 11. A research carried out in 1990 showed that in Nigeria 43.1% of the under-fives were stunted (short for their age), 35.7% were underweight (small for their age) and 9.1% wasted (thin for their height) 12. In 2008, the Nigeria Demographic and Health Survey (NHDS) conducted indicated that 41% of Nigeria children are stunted, 23% are underweight and 14% are wasted 13. Comparing these two findings, one would see that not much has changed in the trend and it should be obvious that malnutrition in the under-fives in Nigeria is still a major problem. Of Nigeria's 140.4 million people, an estimated 23.5% are infants and preschool children aged 0-59 months 14; 67.8% of these children are living in the rural areas 13 while the rest 32.2% live in urban centres.
Annually in Nigeria, an estimated 8000 children die from malnutrition before reaching four years of age 15. Since malnutrition leads to impaired mental and physical development of these children, it fundamentally constitutes impairment to the social and economic development of the developing countries like Nigeria. This has however persisted despite many strategies adopted to tackle it by various levels of governmental and non governmental agencies.
Previous literatures on surveys of nutritional and health status of under-five children in Nigeria are few and were mostly carried out in urban areas with little attention being paid to rural areas 15-20, leaving in total oblivion, the fact that Nigeria is a Sub-Saharan Africa developing country with about 70% of the population living in the rural areas. The 2008 NDHS have national representation covering both rural and urban settings; it is new and not yet explored by researchers specifically with respect to malnutrition in under-five children. This study is however out to cover the whole of the country since NDHS provided data that has national representation
In addition, the under-five children are of particular interest because of the pronounced effects of malnutrition in them-malnutrition is a major cause of high morbidity and mortality in them 21. The most severe effects of malnutrition are concentrated in the under-five children that even; if nutrition improves from that time forward, they are most likely to suffer from below normal growth which would affect their physical and mental development, thereby compromising the future of these children, their communities and their countries at large 22. In the light of these, the importance of the aim of this study cannot be overemphasized.
A recent household expenditure survey states that over 50% of the households in the country live below poverty line 23. Poverty has been found out to be the main cause of malnutrition in Nigeria, especially in the rural settlement areas where they mostly practice subsistence agriculture with little income generation to take care of family needs. Malnutrition is a major concern of government of Nigeria which has been working hard to eliminate it by intervening where there is deficiency. Under-nutrition according to a recent comparative risk assessment is estimated to be the largest contributor to the global burden of disease in children 7;24. Furthermore, in most of the developing countries, malnutrition is mutually reinforced by infections which is still very common in these countries and both continue to assume an ever present and alarming threat 25. It has recently been estimated that problems involving interaction of malnutrition and infection still affect three-quarters of the world's inhabitants (mostly the under-fives because of their fledgling immune system) and account for majority of deaths recorded in them 25. Malnutrition causes an increased susceptibility to infections; also infections lead to increased requirement for nutrients by hyper catabolism and increased losses of body constituents subsequently. Often, there is additionally a decreased dietary intake, and together, these can result in precipitation of acute deficiency states in the under-fives who are marginally compensated before the infections. A vicious cycle can be started, which if not promptly and properly treated, can result in death 25. To break this cycle is immunisation which plays a vital role in protecting growth of the under-fives by preventing infectious diseases from occurring in them.
From studies carried out in the past, it is clearly evident that childhood malnutrition is linked to a number of environmental and socioeconomic factors like poverty/wealth index. According to studies by 26;27, there are noticeable disparities between children from rich and those from poor families where children from poor homes suffered more from underweight compared to those from rich homes. Regarding place of residence (rural/urban) 27, the study found stunting and underweight to be more amongst children from rural settings than those from urban settings. Household headed by female have their children suffered from both stunting and underweight according to a study 26. Maternal and paternal educational levels were also found to greatly influence the nutritional status of children as those children whom their parents had high formal education were better off than those whose parents had low or no formal education and specifically maternal education was found to be more associative with malnutrition 26;28. Having access to health care services was also found to be significant in determining nutritional status of children as the children who did not have access to health care facilities suffered mostly from stunting 29. Different geographic regions of Botswana exhibit different socioeconomic development as well as climatic conditions variations and food production which were likely to have been the reasons for the significance association between regions and children's nutritional status independently of individual's household's socioeconomic status according to a study 30. Some demographic factors such as mother's age at child's birth and child's sex were strongly associated with stunting, underweight, as well as wasting 30-33.Child's age was also evident to have significant effect on child's nutritional status as children under age three suffered more from stunting and underweight than those older than three years. Breastfeeding 34 and duration 35 were also found to have influence on nutritional status as those that were not breastfed or have shorter breastfeeding duration had stunted growth. Birth interval and child's birth weight have also been associated with malnutrition according to the studies conducted by some authors 36-39. Furthermore, some studies have shown disproportional burden of malnutrition on children from deprived households 36;40 Other studies linked malnutrition to morbid conditions like respiratory and diarrhoea infections 33 and diseases caused by parasites 41. To provide reliable and accurate information for policy making and programme design that aims at addressing nutritional deficiencies in under-five children, studies that combine child's factors, parent's demographics, environmental and socioeconomic factors in a single analytical framework will be needed of which this study promises to do.
The discussion of this study will therefore be based on the non clinical factors as well as some morbidity conditions that can have effect on the nutritional status of under-five children in Nigeria using the internationally accepted anthropometric parameters such as underweight (weight for age), wasting (weight for height) and stunting (age for height). The main focus of the study will be to analyze, identify and to quantify the effect of major factors that determine nutritional status of children based on which both governmental and non governmental health agencies can use to intervene in a bid to totally eradicate or minimise this public health menace. In addition, the outcome of this study will help to monitor intervention programs set out for malnutrition control in Nigeria to see how effective they are.
Methods and Materials
Nigeria is a country located in West Africa around the Gulf of Guinea. It covers a total area of about 923,768 kilometre squared. In the world, Nigeria is the thirty-second largest country in terms of land mass after Tanzania which is the thirty-first largest. It is the most populous country in Africa continent. The population and housing census conducted by Nigeria Population Commission (NPC) in 2006 puts her population at 140,431,790. The rural area has about 67.8% of the population while the urban area has about 32.2%. The population density of Nigeria is about 150 people per squared kilometre. There are more than 250 ethnic groups in Nigeria with varying languages, customs and cultures thereby creating a nation with rich ethnic diversity. The largest ethnic groups are the Yoruba, Hausa/Fulani and Igbo which account for 68% of the total population. About 27% of the population comprise of Ijaw, Kanuri, Tiv, Nupe, Edo and the Ebiras while the remaining 5% is made up of the other minority groups. The Nigeria Demographic and Health Survey carried out in 2008 puts under five children's population at 17.1% of the country's population which make every unit change in their health to have toll effect on each household's economy and by extension on Nigeria's economy and productivity.
Cross sectional and population based study using data obtained from 2008 Nigeria Demographic and Health Survey.
Data source/Sampling technique
This study will be based on 28,647 under five children included in Nigeria Demographic and Health Survey (NDHS) in 2008. The NDHS collected data on demographic, environmental, socioeconomic, and health issues from a nationally representative sample of 34,596 women aged 15-49 years in 36,800 households that were eligible to be interviewed. The country by stratification was divided into 36 states and the Federal Capital Territory (FCT) all within the six geopolitical zones 13. Domain was set up and each domain is made up of enumeration areas that was established by the general population and housing census conducted in 2006 13. The sampling frame is made up of a list of all enumeration areas (clusters) 13. From each domain, a two stage probabilistic sampling method was used for the clusters selection 13. The first stage involved choosing of 888 primary sampling units (PSUs), 602 in the rural and 286 in the urban areas with a probability proportional to the size 13. The size in this context is the number of households in each cluster. A second stage of sampling followed the first stage which involved the systematic sampling of households from the selected enumeration areas 13.
Approval was granted for secondary analysis of existing data after the removal of all identifying information of the respondents by the Ethics Committee of the ICF Macro at Calverton in the USA in conjunction with the National Ethics Committee of the Federal Ministry of Health in Nigeria. The data were got by these bodies through pre test questionnaire (questions and anthropometric measurements) after informed consent was obtained from mothers of the children that were eligible for the survey.