LAUSR

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. 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. 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. 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.