Pneumonia is the leading cause of death in children under 5.

Judge as of 2022 using the most recent authoritative cause-of-death estimates. True: pneumonia (or lower respiratory infections) ranks first among all causes of under-5 death in WHO, UNICEF, MCEE or IHME GBD data. Mostly true: pneumonia ranks first among infectious causes, or first among single diseases, while a grouped category ranks higher overall (e.g. preterm birth complications or neonatal disorders), and authoritative bodies such as UNICEF commonly describe it as the leading cause. Mixed: sources split, with some ranking it first and others clearly second. Mostly false: pneumonia is a major cause but clearly ranks below one or more single causes across the main sources. False: pneumonia is not among the top few causes.

Set before the research began.

1. E1 Global, regional, and national causes of under-5 mortality in 2000-19: an updated systematic analysis with implications for the Sustainable Development Goals Lancet Child & Adolescent Health (PubMed record) · 1 November 2021

   “primarily due to preterm birth complications (17·7%, 16·1-19·5), lower respiratory infections (13·9%, 12·0-15·1), intrapartum-related events (11·6%, 10·6-12·5), and diarrhoea (9·1%, 7·9-9·9)”

2. E2 Pneumonia in children World Health Organization · 11 November 2022

   “Pneumonia is the single largest infectious cause of death in children worldwide. Pneumonia killed 740 180 children under the age of 5 in 2019, accounting for 14% of all deaths of children under 5 years old”

3. E3 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.”

The evidence shows pneumonia (lower respiratory infections) ranks first among infectious causes but behind preterm birth complications overall [E1][E2], and WHO lists it after intrapartum-related events [E3]. No evidence item shows authoritative bodies such as UNICEF commonly describing it as the leading cause, which the mostly-true criterion requires, so the evidence does not settle which criterion applies.