Chapter Six
CONCLUSION
Summary of thesis results and conclusions
This dissertation examined malnutrition and mortality among Bolivian children in the late 1980s and changes in their mortality risk before this period. Data from the Bolivian Demographic and Health Survey formed the basis for this analysis. The results of this dissertation were presented in three analytic chapters on changes in mortality rates during the last 30 years; on high-altitude hypoxia, genetic inheritance, malnutrition, and child height; and on neonatal and post-neonatal mortality examined by cause of death.
In Chapter Three, application of the Brass and Feeney indirect estimation techniques to the DHS data and other surveys showed that child mortality rates have been falling quite rapidly over the last 15 years. Examination of macro-level data revealed that several commonly cited explanations of mortality decline -- urbanization, increases in GDP per capita, improvements in nutrition, expansion of primary health care and fertility changes -- are implausible explanations of the Bolivian experience. Based on the available evidence, the most likely explanation for this rapid mortality decline is that the expansion of the educational system resulted in a shift in the social composition of births toward women with higher levels of education who experience lower rates of child mortality.
There are two main conclusions drawn from this analysis. First, the health transition in Bolivia began prior to the major medical interventions of immunization and oral rehydration therapy. Bolivia is not the only example of this phenomenon, one need only look at the 19th century experience of European countries. The second conclusion is that this transition occurred at a time of modernization in Bolivia, which was chiefly associated with expansion of the educational system. In Bolivia, the spread of mass education is causing a linguistic transformation, the supplanting of the indigenous languages of Aymara and Quechua by Spanish. In Bolivia, knowledge of Spanish has been a prerequisite for access to modern ideas, information, and technologies, which are the forces assumed to be responsible for this health transition.
In Chapter Four, elevation data were added to the DHS data set to allow simultaneous analysis of the impact of high-altitude hypoxia, genetic inheritance, and malnutrition on child height. Multivariate regression analysis of height Z-scores demonstrated that the slow growth of Bolivian children was principally a reflection of chronic malnutrition rather than genetic adaptation or hypoxic stress from high altitudes. However, while not being the principal cause of slow growth, the effect of high-altitude hypoxia appeared to be large enough to warrant reconsideration of the use of a single international child growth standard. In Bolivia, use of this growth standard would result in the erroneous conclusion that malnutrition is concentrated in the Altiplano region. In fact, malnutrition is widespread throughout all of Bolivia.
Chapter Five analyzed neonatal and postneonatal mortality using a proximate determinants framework. Maternal education was found to have a strong impact on both neonatal and postneonatal mortality independent of husband's education, husband's occupation, and family and geographic characteristics. It appeared that education acted through four key proximate factors to explain differences in neonatal mortality: residence in homes without sanitation facilities, lack of tetanus immunizations, lack of medical assistance at delivery, and delivery of low birthweight babies. However, closer examination of the impact of these bio-medical factors on specific causes of death indicated that most were proxying for some unmeasured behaviors.
In the postneonatal analysis, the proximate determinants appeared not to mediate the effects of maternal education. This was most likely due to an incomplete list of proximate determinants for the postneonatal period. Examination of cause of death revealed that educational differentials only existed for mortality from diarrhea and not for mortality from respiratory and non-infectious causes. Due to data limitations, this analysis was unable to determine the bio-medical linkage between maternal education and child survival -- a causal explanation of this relationship remains elusive.
There are two conclusions drawn from this chapter. First, we remain uncertain about the role played by maternal education in reducing child mortality. Several authors (Caldwell, 1989; Cleland and van Ginnekan, 1989) have suggested that domestic child care practices may be a central explanation of the increased survival of children of better educated mothers. This analysis tends to support this view by demonstrating that the advantage in child survival of children of better educated mothers is due to lower mortality rates from diarrheal disease rather than airborne and non-infectious diseases. Reduction in exposure to diarrheal pathogens and prevention of death from diarrheal dehydration can be accomplished through adoption of new domestic child care behaviors. Proof of this relationship awaits detailed studies of child care practices in a developing country setting such as that carried out by the Cebu group (Cebu Study Team, 1991). The second is that considerable caution should be exercised in health studies which attempt to attribute differences in mortality to health behaviors and interventions without considering cause of death data. It was shown in this analysis that correlations between presumed bio-medical factors and child mortality are often spurious.
The advantages of large-scale health surveys such as the DHS lie in their standardization and hence the ease of comparative analyses between countries. A natural extension of this dissertation would be to apply each of this dissertation's three analyses to the full collection of DHS countries. First, Chapter Three's decomposition of mortality decline into rate and composition effects could be examined among all 51 DHS countries. This would assess the potential contribution of compositional shifts accompanying modernization such as expansion of educational systems, fertility decline, and urbanization in reducing aggregate infant mortality.
Second, the analysis in Chapter Four of the effect of altitude on the height of children can be carried out in other countries with mountainous regions in which the DHS collected child measurements. These countries are Guatemala in Central America; Colombia and Peru in South America; Uganda, Rwanda, Burundi, and Tanzania in Africa; and Pakistan in Asia. This more general analysis could attempt to confirm the existence of an altitude effect similar to that observed in the United States and Bolivia. Such a study would examine the role of this effect in biasing our estimates of malnutrition within and between countries.
Third, the study of cause of death data in Chapter Five can be extended to the six other countries in which DHS collected cause of death information: Cameroon, Egypt, Morocco, Namibia, Senegal, and Yemen. In Bolivia, the child survival advantage conferred by maternal education was only associated with reduction in deaths due to diarrheal disease. Is this finding also true of these African countries? Further, it was shown that many associations between bio-medical factors and child mortality appear to be spurious. Should this prove true in these other DHS countries, it would cast doubt on the usefulness of analysis of mortality determinants using infant or child mortality as a health outcome without considering the cause of death.
This dissertation also suggests that better use can be made of existing data sets. Most of the DHS surveys are based upon samples drawn from a national population survey or census. This analysis made use of the Bolivian National Population and Housing Survey to provide information about the ethnic composition and residential location of communities sampled in the DHS Bolivia. In general, these surveys or censuses can provide many types of community-level information which may be missing or inaccurately measured in the DHS.
The dissertation began with the question: "What can demography tells us about the health transition?" In the case of Bolivia, the answer has been two-fold. First, though its infant mortality rate is among the highest in the Western Hemisphere, Bolivia is in the midst of a dramatic health transition. Despite considerable economic difficulties and limited health and economic infrastructure, child mortality rates have been declining for the past 15 years. Second, maternal education is a major determinant of differentials in malnutrition and mortality. In the case of mortality, children of better educated mothers are at lower risk of diarrheal death, independent of wealth, sanitation, and other factors. This finding provides strong evidence that adoption of new child care behaviors is an important determinant of child survival and suggests that expansion of educational opportunities for women has been a central feature of the decline in Bolivian child mortality.