Almost half of all deaths in children under the age of five is a result of undernutrition (UNICEF, 2018). Stunting, meaning reduced linear growth, is the most prevalent form of undernutrition and a major problem worldwide, with 155 million children under five being stunted in 2016 (UNICEF, World Health Organisation (WHO) and the World Bank, 2017). The first of the six ‘Global Nutrition Targets 2025’ is therefore, to reduce the number of stunted children under five by 40%, compared to 2012 (WHO, 2012). Worldwide, stunting prevalence declined between 2000 and 2016, suggesting overall positive trends. Except, at the same time in West and Central Africa, stunting numbers increased from 22.9 to 28.1 million children under five (UNICEF, 2018).
Rwanda is a small country in Central and East Africa. It is one of the countries making remarkable progress on the Millennium Development Goals (MDGs) (USAID, 2014). Nevertheless, child mortality and undernutrition remain, as in other African countries, a serious challenge. Between 2000 and 2015, stunting in children under the age of five decreased in Rwanda. Despite, numbers are still high and of major concern. In 2000, 51% of children under the age of five were stunted in Rwanda, and in 2015 this is still almost 4 in 10 (38%) children (Demographic and Health Survey (DHS), 2015). With this current trend, the ‘Global Nutrition Target 2025’ on stunting reduction will not be reached in Rwanda (European Commission, 2017).
Children are defined stunted when their height/length-for-age z-score is more than two standard deviations below the WHO Child Growth Standards median (H/LAZ z-score < -2), between the age of 0-5. Stunted children fail to reach their linear growth potential, because of suboptimal health conditions and inadequate nutrition and care, according to the description of stunting by the WHO (WHO, n.d.). Impaired growth, as a result of stunting, associates with severe, irreversible physical and cognitive damage, especially when occurring during the first 1000 days, from conception through the first two years of life (WHO, n.d.). Associations between stunting and morbidity and mortality risk, risk of chronic diseases in adulthood, and learning capacity and productivity are frequently reported (Onis & Branca, 2016). Therefore, linear growth during childhood serves as a marker for multiple health aspects later in life.
The most important determinants of stunting, based on epidemiological studies, seem to be suboptimal breastfeeding and complementary feeding practices, recurrent infections and micronutrient deficiencies (Prendergast & Humphrey, 2014). However, more factors are involved which have been captured in the WHO Conceptual Framework on Childhood Stunting (Stewart et al., 2013). This framework includes consequences, causes and context determinants of stunted growth and development, and can be found in Appendix 1. Causes for childhood stunting are grouped into four categories: household and family factors, inadequate complementary feeding, breastfeeding, and infections (Stewart et al., 2013). In Rwanda, the most important factors associated with stunting are previously reported to be: poor quality and availability of food, repeated illness and poor health care, lack of knowledge on feeding practices, and inadequate access to WASH (Water, Sanitation and Hygiene) (Lu et al., 2016).
Besides illness being a risk factor for stunted growth, stunted children also face an increased risk of multiple diseases and infections (Prendergast & Humphrey, 2014). Poor linear growth is associated with higher susceptibility to infectious diseases, probably due to impaired immune function (Solomons, 2007). Undernutrition mainly increases the risk on illness from common childhood infections, like diarrhoea, respiratory infections, malaria, HIV and AIDS, and measles (Black et al., 2008; Richard et al., 2013). Besides, stunting often goes together with nutrient deficiencies, like vitamin A, iron or zinc. These can, subsequently, cause various diseases such as blindness, anaemia and neural tube defects (UNICEF, 2013). Furthermore, severely stunted children have a four times higher risk of mortality, compared to well-nourished children (Black et al., 2008). In 2009, stunting contributed to nearly 50% of morbidity and mortality among children under five years of age in Rwanda (Lu et al., 2016).
The association between stunting and morbidity is described as a vicious cycle in a report on child nutrition by UNICEF (2013): children are more likely to suffer from diseases when stunted, and diseased children are more likely to become stunted. As being a cause of stunted growth, breast and complementary feeding practices are associated with both stunting and morbidity (Stewart et al., 2013). The WHO recommendations on infant feeding practices are categorized in eight Infant and Young Child Feeding (IYCF) core indicators (Appendix 2) (WHO, 2008). The first indicator, exclusive breastfeeding up to six months, seems to reduce the risk on morbidity, especially from infectious diseases (Kalanda et al., 2006; Kramer et al., 2001; Bhandari et al., 2003). Furthermore, early introduction of complementary foods is found to increase the risk on morbidity (Kramer et al., 2001; Kalanda et al., 2006). On the other hand, high morbidity is associated with early introduction of complementary foods, and mixed feeding. Thus, infant feeding practices are often being changed by the mother or caregiver when the child is ill. This is called reverse causality (Marquis et al., 1997).
The concept of reverse causality is also studied for the association between growth and IYCF practices. Before, exclusive breastfeeding was thought to be negatively associated with growth (Victora et al., 1992; Brakohiapa et al., 1988). Later it was found that, instead of increased breastfeeding leading to poor growth, children’s lack of growth can lead to a change in feeding practices, and thus increased breastfeeding (Marquis et al., 1997). So, mothers might be influenced in their feeding practices by both illness and growth of their children (Piwoz et al., 1994; Marquis et al., 1997). Lastly, inadequate IYCF practices are found to be a strong predictor of stunting under the age of five (Stewart et al., 2013; Espo et al., 2002). The two-sided associations between stunting, morbidity and IYCF practices are visualized in Figure 1.
Figure 1 The associations between inadequate feeding practices, morbidity and stunting
In Rwanda, respiratory tract infections, diarrhoea and malaria are among the top five causes of death. The incidence of each of these diseases is more than ten percent among children under five, according to the DHS 2015. This, combined with high stunting rates in Rwanda, makes it important to investigate the associations between morbidity and stunting in this country. To be able to further reduce the prevalence of stunting in Rwanda, as well as in other developing countries, we need to define these associations in order to design possible interventions.
1.1. Objective
The aim of this Master thesis is to investigate the association between child morbidity and longitudinal growth, related to stunting, over the first nine and twelve months of life in new-borns in Rwanda with the available data from the GORILLA study.
To reach this aim, the following study questions, supported by sub-questions, are set up and answered in this thesis.
Primary study question:
What is the association between total morbidity and the growth of Rwandan children during the first nine or twelve months of life?
– Which specific morbidity causes (diarrhoea, malaria or respiratory tract infections) contribute significantly to this association, if present?
– How is this association affected by effect modification from breast- and complementary feeding, and stunting?
Secondary study question:
What is the association between events of morbidity and stunting, defined by a LAZ ≤ -2, of children at nine and twelve months?