More than four million children under five die each year in low- and middle-income countries, and most of those deaths are preventable.

Two parts: under-five deaths in low- and middle-income countries exceed 4 million a year, and most of them are preventable. True: the latest UN IGME or WHO estimates available in 2026 put annual under-five deaths in these countries above 4 million, and authoritative sources describe the majority as preventable or treatable. Mostly true: the deaths figure is just under 4 million (for example 3.9M) or depends on how 'young children' is defined, while the preventability part holds. Mixed: one part holds and the other clearly fails. Mostly false or false: the deaths are well below 4 million and/or most of them are not considered preventable.

Set before the research began.

1. E1 Progress in reducing child deaths slows as 4.9 million children die before age five World Health Organization · 18 March 2026

   “An estimated 4.9 million children died before their fifth birthday in 2024, including 2.3 million newborns, according to new estimates released today. Most of these deaths are preventable with proven, low-cost interventions and access to quality health care.”

2. E2 Child mortality (under 5 years) World Health Organization · 1 May 2026

   “The leading causes of under‑five death are preterm birth complications, intrapartum‑related events (birth asphyxia/trauma), pneumonia, diarrhoea and malaria, all of which are largely preventable or treatable.”

3. E3 Levels & Trends in Child Mortality Report 2025 UN Inter-agency Group for Child Mortality Estimation (UN IGME), hosted on DevelopmentAid · 26 September 2026

   “Deaths due to preventable or treatable causes remain concerningly high.”

4. E4 Child mortality (under 5 years) World Health Organization · 1 May 2026

   “The vast majority of newborn deaths take place in low and middle-income countries.”

WHO and UN IGME estimate 4.9 million under-five deaths worldwide in 2024 and say most are preventable or treatable with proven, low-cost interventions (E1, E2, E3). The evidence gives no separate low- and middle-income country total. E4 says only that the vast majority of newborn deaths occur in these countries, so a figure above 4 million for them is a strong inference rather than a direct estimate. The preventability part holds clearly, and the deaths part is well supported but indirect.