Philosophiae Doctor - PhD / This study is based on the assumption that the under-five mortality rate, in recent decades, has declined, particularly in developing countries. However, all the social strata across many countries do not seem to benefit from this reduction of mortality - and mortality remains abnormally high among children especially those from underprivileged social strata. This research is, therefore, a holistic approach to analyse and quantify the inequalities of health among children under five in sub-Saharan Africa over the last two decades (1990-2010). The research sought to investigate the trend and determinants of health inequalities of under-five years (mortality and morbidity) in sub-Saharan Africa (SSA) from 1990 to 2010. An essential point has been devoted to the decomposition of effects and analysis of the contribution of the factors explaining these inequalities. The data used in the study come from Demographic and Heath Surveys (DHS) done between 1990 and 2015 in sub-Saharan Africa countries. In order to analyse the inequalities in trends of mortality and morbidity of children, different selected countries that have conducted at least three DHS during the 1990-2010 period. Several statistical methods were used for data analysis. There were four chapters which is prepared with an article style. For the first paper titled "Decomposing Inequalities in Under- Five Mortality in Selected African Countries", concentration index (CI) and Generalised Linear Model (GLM) with a logit link were used to analyse and measure under 5 mortality inequalities and the associated factors. This paper has been published in the Iranian Journal of Public Health. For the second paper titled "Determinants of Under-Five Mortality in Burkina Faso: A Concentration Dimension". The study used logistics regression and Oaxaca-Blinder decomposition method for the binary outcome to analyse data was involved. For data analysis of the third paper titled "Women Education, Health Inequalities in Under-Five Mortality in sub-Saharan Africa, 1990 – 2013", logistic regression and Bius's decomposition method were used to examine the effect of mother's education level on childhood mortality. In the fourth paper titled "Trends and Risk Factors for Childhood Diarrheal in sub-Saharan Countries (1990-2010): Assessing the Neighbourhood Inequalities", a multilevel logistic regression modelling was used to determine the fixed and random effects of the risk factors associated with the diarrheal morbidity. The work carried out during this on-going thesis helps to understand the magnitude of inequalities in under-five mortality in sub-Saharan countries. The findings showed that the contributing factors of inequalities of child mortality were birth order, maternal age, parity and household size. With regards to the relationship between mother's education level and inequalities in mortality of children under-five in sub-Saharan Africa, findings showed that children of mothers who did not attend school have a higher rate of death compared to those who had been to school. However, we have observed that the inequalities have narrowed over time. The results showed the risk factors of diarrheal morbidity varied from one country to another, but the main factors included: child's age, the size of the child at birth, the quality of the main floor material, mother's education and her occupation, type of toilet, and place of residence. In conclusion, the results of this study show that inequalities in under-five mortality are still important among different social strata in sub-Saharan Africa countries. It is then urgent to take actions to save the lives of children in disadvantaged social strata. / National Research Foundation

<p>The present study was conceived to examine the trend and factors affecting fertility in Nigeria and Guinea. Fertility has declined by about nineteen percent in Nigeria between 1982 and 1999. In the same period it has declined by five percent in Guinea. The decline is observed in data from censuses and surveys. Studies have reported that fertility transition is in progress in most Sub-Sahara African countries (Bongaarts 2008 / Guttmacher 2008), Nigeria (Feyisetan and Bankole 2002) and Guinea (measuredhs 2007). Studies and surveys done in some regions and among ethnic groups suggest that fertility is declining in Nigeria (Caldwell et al. 1992) and Guinea (measuredhs 2007). However, these studies and surveys are devoid of national representativeness as they are localized in specific regions or selected ethnic groups. Thus, they cannot be used as a national reference. The trend of the total fertility rate (TFR) from the three consecutive Demographic and Health Surveys in Nigeria did not show any meaningful decrease over time. In the same vein, no evidence of fertility decline was observed in Guinea from the Demographic and Health Surveys. The claim that fertility is declining in these two countries which assures the funding organizations that Family Planning programs are successful is beyond the scope of the present study. Based on Demographic and Health Surveys the claim that fertility is decreasing in Nigeria may be misleading, whereas in Guinea fertility has shown stability. This suggests that while the factors affecting fertility may be similar, their impacts differ from country to country.</p>

<p>The present study was conceived to examine the trend and factors affecting fertility in Nigeria and Guinea. Fertility has declined by about nineteen percent in Nigeria between 1982 and 1999. In the same period it has declined by five percent in Guinea. The decline is observed in data from censuses and surveys. Studies have reported that fertility transition is in progress in most Sub-Sahara African countries (Bongaarts 2008 / Guttmacher 2008), Nigeria (Feyisetan and Bankole 2002) and Guinea (measuredhs 2007). Studies and surveys done in some regions and among ethnic groups suggest that fertility is declining in Nigeria (Caldwell et al. 1992) and Guinea (measuredhs 2007). However, these studies and surveys are devoid of national representativeness as they are localized in specific regions or selected ethnic groups. Thus, they cannot be used as a national reference. The trend of the total fertility rate (TFR) from the three consecutive Demographic and Health Surveys in Nigeria did not show any meaningful decrease over time. In the same vein, no evidence of fertility decline was observed in Guinea from the Demographic and Health Surveys. The claim that fertility is declining in these two countries which assures the funding organizations that Family Planning programs are successful is beyond the scope of the present study. Based on Demographic and Health Surveys the claim that fertility is decreasing in Nigeria may be misleading, whereas in Guinea fertility has shown stability. This suggests that while the factors affecting fertility may be similar, their impacts differ from country to country.</p>

Background: The present study was conceived to examine the trend and factors affecting fertility in Nigeria and Guinea. Fertility has declined by about nineteen percent in Nigeria between 1982 and 1999. In the same period it has declined by five percent in Guinea. The decline is observed in data from censuses and surveys. Studies have reported that fertility transition is in progress in most Sub-Sahara African countries (Bongaarts 2008; Guttmacher 2008), Nigeria (Feyisetan and Bankole 2002) and Guinea (measuredhs 2007). Studies and surveys done in some regions and among ethnic groups suggest that fertility is declining in Nigeria (Caldwell et al. 1992) and Guinea (measuredhs 2007). However, these studies and surveys are devoid of national representativeness as they are localized in specific regions or selected ethnic groups. Thus, they cannot be used as a national reference. The trend of the total fertility rate (TFR) from the three consecutive Demographic and Health Surveys in Nigeria did not show any meaningful decrease over time. In the same vein, no evidence of fertility decline was observed in Guinea from the Demographic and Health Surveys. The claim that fertility is declining in these two countries which assures the funding organizations that Family Planning programs are successful is beyond the scope of the present study. Based on Demographic and Health Surveys the claim that fertility is decreasing in Nigeria may be misleading, whereas in Guinea fertility has shown stability. This suggests that while the factors affecting fertility may be similar, their impacts differ from country to country.Method: Data from the Demographic Health Surveys (DHS) conducted in Nigeria and in Guinea were used in the study. Trends in TFR by background were extracted from the censuses and DHS final reports in Nigeria and Guinea. Data from DHS 1999 and DHS 2003 in Nigeria and DHS 1999 and DHS 2005 in Guinea were used for the actual analysis. The sample sizes of 8199 and 7620 of DHS 1999 and 2003 respectively for all women aged 15 - 49 were included in Nigeria. The sample sizes for Guinea were 6753 and 7954 for DHS 1999 and 2005 respectively. The trends in knowledge and current contraceptive use, unmet needs,desires for last child, current pregnancy, visiting of health facility, visitation by family planning workers and respondent approval of Family Planning (FP) were examined by age groups. Univariate and bivariate analyses were executed to explain the association and determinants of contraceptive use by socio-demographic characteristics. Stepwise multinomial regression was carried out to determine the variables affecting total number of children ever born (TCB).Result: Total fertility rate has increased in Nigeria between 1990 and 2003 by background characteristics. It has increased by eleven and fourteen percent in rural and urban residence respectively in Nigeria within the same interval. Fertility increased by thirteen and seventeen percent among women with primary and higher education respectively in Nigeria. Unmet needs for child spacing decreased by three percent. Over seventy percent of women have never discussed FP with their partners and other people. Over sixty percent of Women neither visited a health facility (HF) nor were visited by a health worker in 2003. Forty-eight percent of the women approved of FP in 2003, which represents an increase of five percent of 1999.Over ninety percent wanted their last child and current pregnancy in 2003. However, there are incidences of mistimed and unwanted births and pregnancies. There was an association between contraceptive use and all the socio-demographic variables examined. The age of the respondent, current use of contraceptive, age at first sexual intercourse and partner’s education have positive effects on fertility. However, education of women, place of residence and age at marriage has a negative effect on fertility.Total fertility rate has remained stable in Guinea. It increased by eight percent in rural areass and decreased by fifteen percent in urban areass between 1992 and 2005. In Guinea, fertility decreased by over twenty percent for women with primary and secondary education between 1992 and 2005. Unmet needs for child spacing and limiting declined by three and one percent. Over eighty percent of women have not discussed FP with their partners and other people. Women that did not visit a HF remained stable at sixty-six percent, while ninety-two percent were not visited in their homes by a FP worker. The women who approved of FP were forty-seven percent, showing a decline by eleven percent from 1999. Over eighty percent of the women wanted their last child and current pregnancies in 2005. There was an association between contraceptive use and all the socio-demographic variables examined.The significance of the regression coefficient shows that the age of the respondent and current use of contraception has a positive effect on TCB. Education, place of residence, age at marriage and religion have negative effects on TCB.Conclusion: The general patterns observed do not give confidence that fertility is declining or showing a tendency towards declining in Nigeria. In addition the use of modern contraceptive has no bright future as a vehicle to regulate fertility in Nigeria. Fertility in Guinea shows some potential for reduction which may be transitory because some of the indicators that favour fertility reduction seem to be losing their grip. There are overall negative attitudes to contraceptive use and FP in Guinea. This is similar to the observed situation in Nigeria. Expectation that intensified campaigns on contraceptive use and FP will reduce fertility and ultimately reduce population growth in Nigeria and Guinea is not likely to be met, because the desire for large families abound. / Magister Scientiae - MSc

Magister Philosophiae - MPhil / The present study was conceived to examine the trend and factors affecting fertility in Nigeria and Guinea. Fertility has declined by about nineteen percent in Nigeria between 1982 and 1999. In the same period it has declined by five percent in Guinea. The decline is observed in data from censuses and surveys. Studies have reported that fertility transition is in progress in most Sub-Sahara African countries (Bongaarts 2008; Guttmacher 2008), Nigeria (Feyisetan and Bankole 2002) and Guinea (measuredhs 2007). Studies and surveys done in some regions and among ethnic groups suggest that fertility is declining in Nigeria (Caldwell et al. 1992) and Guinea (measuredhs 2007). However, these studies and surveys are devoid of national representativeness as they are localized in specific regions or selected ethnic groups. Thus, they cannot be used as a national reference. The trend of the total fertility rate (TFR) from the three consecutive Demographic and Health Surveys in Nigeria did not show any meaningful decrease over time. In the same vein, no evidence of fertility decline was observed in Guinea from the Demographic and Health Surveys. The claim that fertility is declining in these two countries which assures the funding organizations that Family Planning programs are successful is beyond the scope of the present study. Based on Demographic and Health Surveys the claim that fertility is decreasing in Nigeria may be misleading, whereas in Guinea fertility has shown stability. This suggests that while the factors affecting fertility may be similar, their impacts differ from country to country. / South Africa

Vécue comme l’une des plus grandes crises qu’a connue notre génération, la propagation du virus du SIDA est une urgence mondiale sans précédent, notamment en Afrique sub-saharienne où vivent la grande majorité des individus séropositifs. Dans un contexte où aucun vaccin n’existe encore et où les traitements sont onéreux et peu accessibles, les campagnes d’information sur le virus et l’acquisition de connaissances sur les méthodes de prévention, notamment à travers les programmes scolaires, sont cruciaux. La scolarisation est souvent vue comme la solution pour enrayer la propagation du virus et plusieurs études effectuées en Afrique sub-saharienne ont effectivement montré que les individus scolarisés étaient souvent les mieux renseignés sur le VIH/SIDA et son mode de propagation. Au Cameroun, pourtant, la partie de la population qui est la plus touchée par la séropositivité est aussi la plus instruite. C’est sur cet apparent paradoxe que se penche la présente étude. Cette recherche explore les différents facteurs qui sous tendent la relation positive entre le niveau d’instruction et la séropositivité au Cameroun en analysant les données de l’Enquête Démographique et de Santé (EDS) de 2004. Les résultats des analyses bivariées montrent que plus le niveau d’instruction des hommes et des femmes camerounais augmente, mieux ces derniers sont informés sur le VIH et ses modes de transmission. Malgré cet avantage au niveau des connaissances, l’analyse confirme un lien positif entre le niveau d’instruction et la séropositivé fort et statistiquement significatif parmi les femmes camerounaises, mais non significatif chez les hommes. Les résultats des analyses logistiques hiérarchiques suggèrent que c’est une combinaison de facteurs qui explique pourquoi les femmes les plus scolarisées sont aussi les plus touchées par le VIH/SIDA. Le fait qu’elles aient un profil sociodémographique différent (qu’elles soient plus jeunes et plus riches notamment), et qu’elles soient plus urbaines que leurs consœurs moins scolarisées, mais surtout qu’elles aient un temps d’exposition au risque hors union plus long et un nombre de partenaires plus élevés exposent davantage les femmes les plus scolarisées au virus. / Considered the biggest crisis known to our generation, the propagation of the AIDS virus is an unprecedented worldwide emergency, notably in sub-Saharan Africa where the majority of HIV-positive individuals live. In a context where no vaccine exists and where treatments are expensive and difficult to access, information campaigns about the virus and the acquisition of knowledge on prevention, notably through school programs, are essential. Schooling is often seen as the solution to eradicate the propagation of the virus, and studies held in sub-Saharan Africa have actually shown that highest educated individuals are more informed about HIV/AIDS and about its transmission. However, in Cameroon, the most affected part of the population is also the most educated one. This study investigates this apparent paradox. Using the 2004 data from the Demographic and Health Surveys (DHS), this research explores the multiple factors explaining the positive relation between the education level and seropositivity in Cameroon. Result from the bivariate analysis show that the level of knowledge about HIV and its transmission increases with the education level of men and women. In spite of this knowledge advantage, the analysis show a strong, positive and statistically significant link between the education level and seropositivity of women, but this link is not significant with men. The results of the hierarchical logistical analysis suggest that a combination of factor explains why the most educated women are more affected by HIV/AIDS. The fact that those women have a different sociodemographic profile (they are younger and wealthier), and that they live in more urban areas than their less educated counterparts, and especially the fact that they have a longer exposition time to HIV before engaging in a union, as well as an a higher number of sexual partners, increases their exposure to the virus.

Vécue comme l’une des plus grandes crises qu’a connue notre génération, la propagation du virus du SIDA est une urgence mondiale sans précédent, notamment en Afrique sub-saharienne où vivent la grande majorité des individus séropositifs. Dans un contexte où aucun vaccin n’existe encore et où les traitements sont onéreux et peu accessibles, les campagnes d’information sur le virus et l’acquisition de connaissances sur les méthodes de prévention, notamment à travers les programmes scolaires, sont cruciaux. La scolarisation est souvent vue comme la solution pour enrayer la propagation du virus et plusieurs études effectuées en Afrique sub-saharienne ont effectivement montré que les individus scolarisés étaient souvent les mieux renseignés sur le VIH/SIDA et son mode de propagation. Au Cameroun, pourtant, la partie de la population qui est la plus touchée par la séropositivité est aussi la plus instruite. C’est sur cet apparent paradoxe que se penche la présente étude. Cette recherche explore les différents facteurs qui sous tendent la relation positive entre le niveau d’instruction et la séropositivité au Cameroun en analysant les données de l’Enquête Démographique et de Santé (EDS) de 2004. Les résultats des analyses bivariées montrent que plus le niveau d’instruction des hommes et des femmes camerounais augmente, mieux ces derniers sont informés sur le VIH et ses modes de transmission. Malgré cet avantage au niveau des connaissances, l’analyse confirme un lien positif entre le niveau d’instruction et la séropositivé fort et statistiquement significatif parmi les femmes camerounaises, mais non significatif chez les hommes. Les résultats des analyses logistiques hiérarchiques suggèrent que c’est une combinaison de facteurs qui explique pourquoi les femmes les plus scolarisées sont aussi les plus touchées par le VIH/SIDA. Le fait qu’elles aient un profil sociodémographique différent (qu’elles soient plus jeunes et plus riches notamment), et qu’elles soient plus urbaines que leurs consœurs moins scolarisées, mais surtout qu’elles aient un temps d’exposition au risque hors union plus long et un nombre de partenaires plus élevés exposent davantage les femmes les plus scolarisées au virus. / Considered the biggest crisis known to our generation, the propagation of the AIDS virus is an unprecedented worldwide emergency, notably in sub-Saharan Africa where the majority of HIV-positive individuals live. In a context where no vaccine exists and where treatments are expensive and difficult to access, information campaigns about the virus and the acquisition of knowledge on prevention, notably through school programs, are essential. Schooling is often seen as the solution to eradicate the propagation of the virus, and studies held in sub-Saharan Africa have actually shown that highest educated individuals are more informed about HIV/AIDS and about its transmission. However, in Cameroon, the most affected part of the population is also the most educated one. This study investigates this apparent paradox. Using the 2004 data from the Demographic and Health Surveys (DHS), this research explores the multiple factors explaining the positive relation between the education level and seropositivity in Cameroon. Result from the bivariate analysis show that the level of knowledge about HIV and its transmission increases with the education level of men and women. In spite of this knowledge advantage, the analysis show a strong, positive and statistically significant link between the education level and seropositivity of women, but this link is not significant with men. The results of the hierarchical logistical analysis suggest that a combination of factor explains why the most educated women are more affected by HIV/AIDS. The fact that those women have a different sociodemographic profile (they are younger and wealthier), and that they live in more urban areas than their less educated counterparts, and especially the fact that they have a longer exposition time to HIV before engaging in a union, as well as an a higher number of sexual partners, increases their exposure to the virus.

No description available.

La santé des enfants demeure une question prioritaire en Afrique sub-saharienne. Les disparités en matière de mortalité entre pays et au sein des pays persistent et se sont fortement accrues durant la dernière décennie. En dépit de solides arguments théoriques voulant que les variables contextuelles soient des déterminants importants de la santé des enfants, ces facteurs, et particulièrement les influences du contexte local, ont été étudiées beaucoup moins souvent que les caractéristiques individuelles. L'objectif principal de la présente thèse est d’identifier les déterminants individuels et contextuels associés à la mortalité des enfants de moins de 5 ans en Afrique sub-saharienne. L’analyse systématique est basée sur les données les plus récentes des enquêtes démographiques et de santé (DHS/EDS). Deux questions spécifiques sont examinées dans cette thèse. La première évalue la mesure dans la quelle le contexte local affecte la mortalité infanto-juvénile, net des caractéristiques individuelles. La seconde question est consacrée à l’examen de l’effet du faible poids à la naissance sur le risque de décès avant 5 ans. Par rapport à la première question, les analyses multi-niveaux confirment pour plusieurs pays étudiés l’importance simultanée de l’environnement familial et du contexte local de résidence dans l’explication des différences de mortalité infanto-juvénile. Toutefois, par comparaison au contexte familial, l’ampleur de l’effet de l’environnement local paraît assez modeste. Il apparaît donc que le contexte familial reste un puissant déterminant de la mortalité des enfants de moins de 5 ans en Afrique sub-saharienne. Les résultats indiquent en outre que certains attributs du contexte local de résidence influencent le risque de décès des enfants avant 5 ans, au-delà des facteurs individuels dans plusieurs pays. Cette thèse confirme l’effet contextuel de l’éducation sur la mortalité des enfants. Cet effet s’ajoute, dans certains pays, à l'effet positif du niveau individuel d’éducation de la mère sur la survie de l'enfant. Les résultats montrent aussi que le degré d’homogénéité ethnique de la localité influence fortement la probabilité de mourir avant 5 ans dans certains pays. Globalement, les résultats de cette thèse suggèrent que le défi de réduire la mortalité des enfants va au-delà des stratégies visant uniquement les facteurs individuels, et nécessite une meilleure compréhension de l’influence des facteurs contextuels. Par rapport à la deuxième question, les résultats montrent également que les facteurs individuels restent aussi très importants dans l’explication des différences de mortalité des enfants dans plusieurs pays étudiés. Nos résultats indiquent que les différences de mortalité selon le poids à la naissance sont significatives dans tous les pays inclus dans l’analyse. Les enfants nés avec un faible poids (moins de 2500 grammes) courent presque 2 à 4 fois plus de risques de mourir au cours des cinq premières années de vie que les enfants de poids normal, même après correction pour l’hétérogénéité non observée. Ce résultat suggère qu’en plus des mesures visant à réduire la pauvreté et les inégalités de revenus, la réduction de l’incidence du faible poids à la naissance pourrait apporter une contribution majeure aux Objectifs du Millénaire pour le développement; spécialement comme une stratégie efficace pour réduire le niveau de mortalité parmi les enfants de moins de cinq ans. / Child health remains a priority area for health policy in sub-Saharan Africa. Disparities in child mortality between and within countries have persisted and widened considerably during the last few decades. While researchers have devoted considerable attention to the impact of individual-level factors on child mortality, less is known about how community characteristics and institutions affect health outcomes for children, even though they have a prominent role in theoretical models. The aim of this thesis is to identify individual and contextual effects of child mortality by using data from the latest round of Demographic Health Surveys for all countries in sub-Saharan Africa. Two sets of questions are addressed in this research. First, we evaluate the impact of contextual factors on the risk of dying before age 5 net of the effect of individual factors. The results indicate that some attributes of the community influence the mortality risks of children, over and above the intermediate factors included in this investigation. For instance, in half of the countries under study a 1% increase in the proportion of children fully immunized in the community is associated with a decrease of 17-79% in the odds of dying before age 5. The proportion of women in the community completing secondary school also significantly increases child survival. This effect is, in some countries, in addition to the positive individual-level effect of the child’s own mother being educated. Net of individual and household characteristics, higher community-level ethnic homogeneity is associated with decreased odds of dying before age 5 in some countries. Overall, the results of this study therefore suggest that the challenge to reduce under-five mortality goes beyond addressing individual factors, and requires a better understanding of contextual factors. Second, the study exploits recent national survey data for nine countries in sub-Saharan Africa to investigate the association of LBW and mortality not only in infancy but also during childhood, using a standardized methodology to adjust missing birth weight data from household surveys while accounting for unobserved family-level factors (genetic or behavioral) that may modify the relationship between birth weight and under-five-years mortality. We find evidence of the impact of birth weight on the risk of dying not only in infancy but also during childhood, which remains strong and significant in all countries even after controlling for potential confounding factors. The main policy implication of our findings is that reducing the incidence of LBW may be an important prevention strategy to combating child mortality in sub-Saharan Africa countries.

La santé des enfants demeure une question prioritaire en Afrique sub-saharienne. Les disparités en matière de mortalité entre pays et au sein des pays persistent et se sont fortement accrues durant la dernière décennie. En dépit de solides arguments théoriques voulant que les variables contextuelles soient des déterminants importants de la santé des enfants, ces facteurs, et particulièrement les influences du contexte local, ont été étudiées beaucoup moins souvent que les caractéristiques individuelles. L'objectif principal de la présente thèse est d’identifier les déterminants individuels et contextuels associés à la mortalité des enfants de moins de 5 ans en Afrique sub-saharienne. L’analyse systématique est basée sur les données les plus récentes des enquêtes démographiques et de santé (DHS/EDS). Deux questions spécifiques sont examinées dans cette thèse. La première évalue la mesure dans la quelle le contexte local affecte la mortalité infanto-juvénile, net des caractéristiques individuelles. La seconde question est consacrée à l’examen de l’effet du faible poids à la naissance sur le risque de décès avant 5 ans. Par rapport à la première question, les analyses multi-niveaux confirment pour plusieurs pays étudiés l’importance simultanée de l’environnement familial et du contexte local de résidence dans l’explication des différences de mortalité infanto-juvénile. Toutefois, par comparaison au contexte familial, l’ampleur de l’effet de l’environnement local paraît assez modeste. Il apparaît donc que le contexte familial reste un puissant déterminant de la mortalité des enfants de moins de 5 ans en Afrique sub-saharienne. Les résultats indiquent en outre que certains attributs du contexte local de résidence influencent le risque de décès des enfants avant 5 ans, au-delà des facteurs individuels dans plusieurs pays. Cette thèse confirme l’effet contextuel de l’éducation sur la mortalité des enfants. Cet effet s’ajoute, dans certains pays, à l'effet positif du niveau individuel d’éducation de la mère sur la survie de l'enfant. Les résultats montrent aussi que le degré d’homogénéité ethnique de la localité influence fortement la probabilité de mourir avant 5 ans dans certains pays. Globalement, les résultats de cette thèse suggèrent que le défi de réduire la mortalité des enfants va au-delà des stratégies visant uniquement les facteurs individuels, et nécessite une meilleure compréhension de l’influence des facteurs contextuels. Par rapport à la deuxième question, les résultats montrent également que les facteurs individuels restent aussi très importants dans l’explication des différences de mortalité des enfants dans plusieurs pays étudiés. Nos résultats indiquent que les différences de mortalité selon le poids à la naissance sont significatives dans tous les pays inclus dans l’analyse. Les enfants nés avec un faible poids (moins de 2500 grammes) courent presque 2 à 4 fois plus de risques de mourir au cours des cinq premières années de vie que les enfants de poids normal, même après correction pour l’hétérogénéité non observée. Ce résultat suggère qu’en plus des mesures visant à réduire la pauvreté et les inégalités de revenus, la réduction de l’incidence du faible poids à la naissance pourrait apporter une contribution majeure aux Objectifs du Millénaire pour le développement; spécialement comme une stratégie efficace pour réduire le niveau de mortalité parmi les enfants de moins de cinq ans. / Child health remains a priority area for health policy in sub-Saharan Africa. Disparities in child mortality between and within countries have persisted and widened considerably during the last few decades. While researchers have devoted considerable attention to the impact of individual-level factors on child mortality, less is known about how community characteristics and institutions affect health outcomes for children, even though they have a prominent role in theoretical models. The aim of this thesis is to identify individual and contextual effects of child mortality by using data from the latest round of Demographic Health Surveys for all countries in sub-Saharan Africa. Two sets of questions are addressed in this research. First, we evaluate the impact of contextual factors on the risk of dying before age 5 net of the effect of individual factors. The results indicate that some attributes of the community influence the mortality risks of children, over and above the intermediate factors included in this investigation. For instance, in half of the countries under study a 1% increase in the proportion of children fully immunized in the community is associated with a decrease of 17-79% in the odds of dying before age 5. The proportion of women in the community completing secondary school also significantly increases child survival. This effect is, in some countries, in addition to the positive individual-level effect of the child’s own mother being educated. Net of individual and household characteristics, higher community-level ethnic homogeneity is associated with decreased odds of dying before age 5 in some countries. Overall, the results of this study therefore suggest that the challenge to reduce under-five mortality goes beyond addressing individual factors, and requires a better understanding of contextual factors. Second, the study exploits recent national survey data for nine countries in sub-Saharan Africa to investigate the association of LBW and mortality not only in infancy but also during childhood, using a standardized methodology to adjust missing birth weight data from household surveys while accounting for unobserved family-level factors (genetic or behavioral) that may modify the relationship between birth weight and under-five-years mortality. We find evidence of the impact of birth weight on the risk of dying not only in infancy but also during childhood, which remains strong and significant in all countries even after controlling for potential confounding factors. The main policy implication of our findings is that reducing the incidence of LBW may be an important prevention strategy to combating child mortality in sub-Saharan Africa countries.