BackgroundThis study systematically reviewed the causes of child death across different age groups based on the International Classification of Diseases, 10th Revision (ICD-10) criteria.MethodsA comprehensive search was conducted in seven electronic databases and two search engines to identify all studies examining child mortality in any part of Iran or the entire country. Hand searching, gray literature, and bibliographies were also utilized. Data were synthesized descriptively and through meta-analysis.ResultsA total of 35 studies were included, encompassing 58,519 death cases across various age groups. According to the ICD-10 classification, the most common causes of Neonatal Mortality Rates (NMR) were pregnancy, childbirth, and puerperium-related conditions (41.1%), congenital malformations (19.2%), and certain conditions originating in the perinatal period (14.5%). For Infant Mortality Rates (IMR), the leading causes were congenital malformations (44.0%), pregnancy, childbirth, and related conditions (14.5%), and respiratory and cardiovascular diseases (8.7%). In the age group of 28 days to 5 years, the primary causes of death were pregnancy, childbirth, and puerperium-related issues (27.5%), congenital malformations and chromosomal abnormalities (21.6%), and respiratory and cardiovascular disease (9.3%). For children aged 1 to 5 years, congenital malformations (29.1%), external causes (19.6%), and respiratory and cardiovascular disorders (7.2%) were the most significant causes of death. The meta-analysis revealed that immaturity [0.171 (PI: 0.032–0.561)] in infants aged 0–28 days, and congenital malformations in the age groups of 28 to 1 year [0.261 (PI: 0.166–0.385)] and 28 to 5 years [0.173 (PI: 0.078–0.342)] were the leading causes of death.ConclusionsThe findings of this study provide valuable insights for priority-setting interventions aimed at reducing child mortality according to the prevalence rate of specific causes in different age groups.