Chad, like many low- and middle-income countries, is currently experiencing fast socio-demographic, economic, and population health shifts. However, there seems to be variations at the sub-national level on the cited indices in the country that might affect their public health policy. Using data from the nationally representative survey, 2014–15 Chad DHS, this study found that the odds of children dying before their fifth birthday was high in Chad (130 deaths per 1000 live births). Region of residence, place of residence, ethnicity, education, sex of child, and birth rank and interval were identified as predictors of under-five mortality in Chad.
The majority of under-five deaths occurred among children in the FChari Baguirmi, Lagone Oriental region, Borkou/Tibesti, Tandjile, and Hadjer-lamis, compared to those in Wadi fira. This finding confirms previous studies on the association between regional variations and under-five mortality in other low- and middle-income countries (e.g., Ghana and India [20, 21]). The regional differentials noted might be connected with spatial inequality and variations in social development in these regions, with possibly varying population density, regional development, political as well as economic resources . Surprisingly, children in rural areas had lower odds of under-five mortality, compared to those in urban areas although the statistical significance of this association was attenuated after controlling for confounders in successive models. This finding contradicts the commonly established assumption from numerous researches conducted in Kenya , Nigeria [24, 25], Ghana , and sub-Saharan Africa as a whole  that infants born in urban areas have better access to healthcare services and other necessary health-related services that are critical for child survival and development. Chad is a country with a greater percentage (77%) of its population in rural areas . From this premise, it is possible that most rural areas in Chad are endowed with natural environmental conditions like fresh agriculture products and fresh water sources that are healthier. Comparatively, urban dwellers may be confronted with highly polluted water sources, unhygienic processed food products, overcrowding, and intermixing household occupancies as well as poor sanitary conditions. Therefore, mothers and their young children in urban areas may be highly exposed to these unhealthier conditions that are associated with morbidity and mortality, compared to their rural counterparts.
The study further established that under-five mortality varied by the sex of a child, with male children having higher odds of dying before their fifth birthday, compared with female children. Several studies globally support this finding [17, 29,30,31,32]. Principally, some biological and social reasons have been cited to account for this finding. Biologically, male children are highly susceptible to infections (e.g., neonatal disorders) and are more likely to be born premature. Besides, they have a larger average body size and big head circumference which prolong the time of their mothers’ delivery period [17, 31, 33]. Socially, in some societies, gender discrimination (e.g., feeding and medical care practices) exists among male and female children, with the practices favouring females [17, 31, 33]. The study also established statistically significant association between birth rank and under-five mortality, a finding established in previous studies [24, 34,35,36].
Other findings suggest that children born to mothers with no and low formal education (primary) are more likely to die before their fifth birthday, compared to those whose mothers have secondary/higher education. Plethora of research evidence indicate that mother’s education has a significant association with child survival, which works via both direct and indirect pathways [24, 32, 37,38,39,40]. Mothers who are more educated on good childcare practices are more likely to have prompt healthcare-seeking behaviours for their children [37,38,39,40]. These knowledgeable mothers are also more likely to offer appropriate and timely feeding to their children and observe other hygienic behaviours associated with good health outcomes. Educated mothers, unlike uneducated ones, are also more empowered to take certain decisions against bad socio-cultural practices . Unlike uneducated mothers, educated mothers are also more likely to be empowered economically to afford certain basic necessities (such as child food supplements) and other indirect cost associated with childcare [41, 42]. Similar to previous studies in Nigeria [43, 44], sub-Saharan Africa , and 36 low- and middle-income countries , ethnic variations exist in the association of child mortality in Chad. Specifically, children from Baguirmi/Barma ethnic group had higher odds of under-five mortality, compared to children from Zaghawa/Bideyat ethnic group. The probable explanations for this finding could be the differences in ethno-cultural practices or compositions (e.g., early age of marriage, pubertyrites), socio-demographic characteristics, and socio-economic conditions among the ethnic groups [45, 47].
Strengths and limitations of the study
The strength of this study lies in the use of nationally representative data which support the generalizability of the findings in Chad. The large sample size, high response rate, and the use of valid survey and rigorous statistical methods provide trustworthiness to the obtained results. Similarly, the use of a wide range of multiple hierarchical variables warrant deeper examination of these numerous factors.
Despite these strengths, there are some limitations inherent in this study. First, the cross-sectional nature of the data does not allow us to draw causal inferences but only associations. Second, the outcome variable, under-five mortality, was collected based on retrospective self-report from the mothers, which can distort the accuracy of the results. This study design subjects the data to social desirability and recall bias. For example, some mothers, in their report, may classify stillbirths as under-five mortality. There is also the possibility of underreporting since mothers may find it difficult to reveal information on those unfortunate events in their lives. We also acknowledge that the division of risk factors of child mortality into proximate, intermediate, and distal factors may be arbitrary. For instance, sometimes a region, generally understood as a distal factor, may be a proximate risk factor. The causal chain analysis of health outcomes also includes physiological and pathophysiological causes. However, in this study, the risk factors for under-five mortality did not included these causes since the Chad DHS dataset did not have variables on these factors.