under5

Under-5 refers to children who are under five years of age. In public health and development statistics, the term is most often encountered in relation to the under-5 mortality rate (U5MR), which is the probability that a newborn will die before reaching age five when current mortality conditions persist. U5MR is typically expressed per 1,000 live births and combines mortality in the neonatal, infant, and early childhood periods.

Global data on under-5 mortality are published by organizations such as UNICEF, the World Bank, and the World Health Organization. Since the 1990s, the world has seen a steady overall decline in U5MR, but progress varies by region and country. Higher mortality rates are concentrated in parts of sub-Saharan Africa and South Asia, with disparities linked to poverty, conflict, and access to health services.

A range of factors influences under-5 mortality, including malnutrition, infectious diseases (such as pneumonia, diarrhea, and malaria), neonatal complications, and inadequate access to clean water, sanitation, and quality healthcare. Social determinants—poverty, maternal education, and gender inequality—also play a significant role.

Public health interventions aimed at reducing under-5 mortality include immunization, treatment for common illnesses, nutrition programs, promotion of exclusive breastfeeding, maternal health services, safe water and sanitation, and improved newborn and child care. Data limitations, such as variable registration and data quality, can affect U5MR estimates and interpretation.

Policy relevance: under-5 mortality is a core indicator of child health and development and is central to international targets such as the Sustainable Development Goals, especially the goal to end preventable deaths of children under five by 2030.