This paper provides the new estimates for the prevalence of undernutrition by using an aggregate indicator of anthropometric failure and applying it to the large nationally representative datasets in Tanzania. It also describes the trends and examines the correlates associated with anthropometric failures. Our analysis shows how the conventional indices of stunting, wasting, underweight, when used on their own, miss significant numbers of children who experience multiple anthropometric deficits. We show that this can be avoided by using an aggregate measure known as the composite index of athropometric failure (CIAF) [8]. The prevalence of CIAF stands at 38.2% among under 5 year olds in Tanzania in 2015, which declined from 50.1% in 1991. This is higher compared to the prevalence reported by conventional indices of stunting wasting and underweight. In other countries the prevalence of CIAF was 47.8% in India [12]; 48.4% in Ethiopia [17], 48.3% in Bangladesh [15] and 21.7% in China [14]. Although the proportion of children with multiple anthopometric failure has declined from 2.2–1.5% in 2015, it was reported in another study that these children have a up to twelve times greater risk of early mortality [6]. Therefore, CIAF proves very useful in the detection of children who are at higher risk of death associated with anthropometric failure.
This study further confirms the existence of multiple factors influencing childhood undernutrition in the country. Children, maternal, and household socioeconomic factors were found to be associated with anthropometric failure, which indicates the need to strengthen both nutrition-specific and sensitive interventions that can improve livelihoods and ameliorate main drivers of undernutrition such as poverty, food insecurity and other determinants of health.
In this study, anthropometric failure in the country was strongly associated with characteristics of the household like location, wealth status, and household head characteristics. This corresponds with information from a systematic review, which reported that wealth and socio-economic factors were highly impacting the prevalence of anthropometric failure in many low- and middle‐income countries including Tanzania [32]. Our study found that children living in urban areas are less likely to experience anthropometric failure compared to rural children. This is consistent with previous studies conducted in Bangladesh[15] and Myanmar [26] and is most likely linked to better living conditions, and adequate all years-round food accessibility in urban areas. In addition, our findings show that children from poorer households are at increased risk of anthropometric failure compared with children from richer households. This corresponds to many other studies done previously in developing countries like Ethiopia [17],Bangladesh [15] and India [33]. Pomati et al. [34] analysed the data of several West and Central African countries found that the risk of anthropometric failure among children in wealthier households is half than that of the poorest households. Similarly, highest wealth status was found to be associated with lower odds of undernutrition among children under 5 years old in Tanzania [2], and elsewhere [32]. This might be because poverty is closely associated with inadequate provision of nutritious food and poor sanitation. Both factors are likely to increase the risk for infections and ultimately lead to undernutrition among children [35, 36]. In addition, access to health care services may also be limited in poor households compared to the rich ones.
Households headed by older parents are less likely to have children with anthropometric failure, while household headed by women had a higher likelihood of having children with anthropometric failure. Older parents most likely have more experience concerning childcare and thus make choices that are more infomed on child health, and engage themselves in different knowledge activities than younger parents. In terms of gender of the head of the household, in many cases in the country, female-headed households are single-parent families due to divorce/separation, death of or sometimes abandonment by men. Therefore, they are sole providers and are responsible for childcare duties and income generation, leaving them more vulnerable to food insecurity than male-headed households. This correspond to a study by Haidar et al [27] which found that the proportion of undernutrition was significantly higher in female-headed households. Nutrition interventions of socioeconomically disadvantaged households may thus significantly reduce the burden of undernutrition in the country, as has been stated previously by Alderman et al [37].
This study shows that both maternal and newborn health is an important factor to consider when addressing the nutrition status of children. In this study, we see that a mothers nutritional status, birth weight of children, and place of delivery were associated with anthropometric failure among children. This calls for more efforts focusing on the nutrition of first 1000 days of life, from the conception up to 2 years. This study reveals that children who were born at home have a higher risk of anthropometric failure than those born at a health facility. Similar results were found in a cross-sectional studies in Tanzania [2] and elsewhere [26]. Health facility delivery is very important because it help to receive appropriate and timely obstetric and medical care, as well as information about childcare to parents. Therefore, promoting health facility delivery can have beneficial effect not only on the mothers, but also on their children. On the other hand, good nutritional status of mothers can protect against anthropometric failure. Children of underweight mothers are more likely to get anthropometric failure than those of normal weight mothers. The plausible explanation for this may be poor nutritional status of mothers is a risk to infant deficiency and a risk factor for fetal growth restriction, resulting in low birth weight [38]. We also see that low birth weight have a strong positive relationship with anthropometric failure in this study. This is comparable with findings from Sunguya et al. [2] who reported that children born with normal birth weight were 35% less likely to be stunted than low weight children.
Furthermore, biological factors of children like age and gender can highly influence undernutrition. Children in the youngest age group of 0–6 months had a significantly lower risk of failure than in older age groups of above 6 months. These results are consistent with many other studies from other countries [15, 24] as well as in Tanzania [2, 22, 23]. This may be because of either poor feeding practice of the older children, or sometimes vulnerability to diseases when a child grows from 6 months onwards. Another possible reason for this may be that from 6 months, termination of breastfeeding starts, and children have much physical and mental growth, and by that time, they have to attain a well balanced diet to support the development of the child's brain and body. Young children below the age of two years have to receive adequate complementary feeding in order to be healthy and maintain good growth [30]. Surprisingly, in this study we did not find the association between consumption of a diversified diet and anthropometric failure of children between 6 to 23 months of age in any of the surveys. This study did not figure out the reasons for this observation, however; in our previous analysis, we have shown that dietary diversity was a good predictor of stunting and underweight only, but not wasting among children of 6 to 23 months [31]. Similar results have been reported among under 5 years children in Myanmar [26]. We also have to take into account that, the method of collection of dietary diversity data in recent TDHS of 2010 and 2015 have changed from that of 2005 to accommodate the new indicator suggested by WHO of minimum dietary diversity (MDD) [30]. Nevertheless, this study found that boys are at higher risk of having anthropometric failure compared to girls. This is not unexpected, a study by Wamani et al. [39] conducted among sub-Sahara African countries found that male children under five years of age are more likely to become undernourised than females. There is lack of scientific evidence to justify the presence of risk for boys toward undernutrition. Perhaps the morbidity pattern between male and female children could explain the phenomenon [39].
We also found that childhood anthropometric failure is significantly associated with mother’s educational attainment and employment. However, employment status was significantly associated with anthropometric failure only in 2005, but not in the recent surveys of 2010 and 2015, signifying that women employment was improved over the past 10 years in the country. We also found that, children of mothers who are more educated tend to have a lower likelihood of anthropometric failure. Briefly, educational attainment of the mother may influence the nutritional status of a child in various ways. For example, well-educated women tend to have better work opportunities and obtain higher incomes that may results to higher socioeconomic status. Another reson could be that more educated mothers could understand maternal and child care education and information provided through different media compared to mothers with low education. Endris et al. [17] evaluated the risk factors of undernutrition among children aged 0–59 months in rural Ethiopia and reported that, the odds of being undernourished was 1.32 times higher for children whose mothers did not have any basic education compared to children whose mothers attended primary education. This observation is comparable to our results. The relationship between mother’s education and child nutritional status has been well documented in several other studies [25, 40–42].This study together with the above literature highlight the importance of women education in improving child nutrition status.
Although this study provides a clear picture on the trends of CIAF and the possible correlates from the national data in Tanzania, some general limitations should be mentioned. Analysis on the prevalence and trends included six surveys while factors associated with CIAF were only identified from three recent surveys. It is possible that older surveys could show different associated factors compared to most recent studies. However, the three surveys included that were the most recent ones provide information on the possible areas of intervention. In addition, data on other factors that may contribute to CIAF were not collected during the surveys, for example, data on water hygiene and sanitation and other childcare practices that may contribute to CIAF. It is therefore important to consider these factors in future studies. Despite the above limitations, we hope this study will shed light on key areas for interventions in Tanzania. In addition, this study used large population based data with a representative sample size at national, regional, rural and urban areas, which provides most robust estimates of the whole country, so it can be easily generalised.