Determinants of trends in neonatal, post-neonatal, infant, child and under-five mortalities in Tanzania from 2004 to 2016

BACKGROUND: Under-five mortality is still a major health issue in many developing countries like Tanzania. To achieve the Sustainable Development Goal target of ending preventable child deaths in Tanzania, a detailed understanding of the risk factors for under-five deaths is essential to guide targeted interventions. This study aimed to investigate trends and determinants of neonatal, post-neonatal, infant, child and under-five mortalities in Tanzania from 2004 to 2016. METHODS: The study used combined data from the 2004–2005, 2010 and 2015–2016 Tanzania Demographic and Health Surveys, with a sample of 25,951 singletons live births and 1585 under-five deaths. We calculated age-specific mortality rates, followed by an assessment of trends and determinants (community, socioeconomic, individual and health service) of neonatal, postneonatal, infant, child and under-five mortalities in Cox regression models. The models adjusted for potential confounders, clustering and sampling weights. RESULTS: Between 2004 and 2016, we found that neonatal mortality rate remained unchanged, while postneonatal mortality and child mortality rates have halved in Tanzania. Infant mortality and under-five mortality rates have also declined. Mothers who gave births through caesarean section, younger mothers (< 20 years), mothers who perceived their babies to be small or very small and those with fourth or higher birth rank and a short preceding birth interval (≤2 years) reported higher risk of neonatal, postneonatal and infant mortalities. CONCLUSION: Our study suggests that there was increased survival of children under-5 years in Tanzania driven by significant improvements in postneonatal, infant and child survival rates. However, there remains unfinished work in ending preventable child deaths in Tanzania. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12889-019-7547-x) contains supplementary material, which is available to authorized users.