Data from the Institute for Health Metrics and Evaluation, published by Ourworldindata.org, shows that the leading cause of death in children under five (under-five mortality) is respiratory infections, accounting for 808,920 deaths. In addition, neonatal disorders (babies less than 28 days old) are also a leading cause of under-five mortality.
These disorders include complications of prematurity (649,439 deaths), neonatal asphyxia and trauma (533,250 deaths), and congenital birth defects (501,764 deaths). Other neonatal disorders account for 349,002 deaths, and neonatal sepsis and infections for 203,013 deaths. Young children are also highly vulnerable to other diseases such as diarrhea, malaria, meningitis, and malnutrition.
Under-five mortality rates are often high in low-income countries. The characteristics of the causes of death also tend to differ across countries. For example, in the UK, child deaths tend to be dominated by neonatal complications. However, deaths from infectious diseases, diarrhea, and malnutrition are very low. Conversely, infectious diseases and nutritional deficiencies are major causes of death in low-income countries.
(Read Databoks: [17.7% of Indonesian Toddlers Still Suffer from Nutritional Problems](https://databoks.katadata.co.id/datapublish/2019/01/25/177-balita-indonesia-masih-mengalami-masalah-gizi))