What are the causes?

The causes of under-five death shift as overall mortality rates decline. In low-income countries, infectious diseases cause a majority of the burden, often due to weakened nutrition and sanitation systems and lack of access to basic prevention and treatment interventions. In higher-income nations, deaths are increasingly due to causes that require more complex interventions to address, especially neonatal disorders (including preterm births).

Many of the causes of under-five mortality interact with and compound each other. In addition, there are a number of underlying drivers that can weaken children and increase the likelihood that a child will die from what otherwise would be a serious but not life-threatening condition. For example, children who are malnourished are more likely to die of diarrhea and acute respiratory infections.

Some of these exacerbating underlying factors include:¹

• Poorly resourced, poor quality, inaccessible or culturally inappropriate health and nutrition services
• Food insecurity
• Inadequate feeding practices
• Lack of hygiene and access to safe water or adequate sanitation
• Female illiteracy
• Early pregnancy and lack of birth spacing
• Geographic, political, or financial barriers to accessing health care

Many of the solutions to under-five mortality are well-known. The key lever for reducing under-five mortality is an accessible, quality primary health care system that provides a continuum of care to women before they are pregnant, throughout their pregnancy, while giving birth, and post-partum, as well as to children through the critical first five years of life. For this reason, many efforts to reduce maternal mortality and neonatal mortality will also serve to reduce overall under-five mortality.²