The answer depends on where in the world you’re looking and the age of the child. Globally, prematurity is the single leading cause of death in children under 5, responsible for 18% of all deaths in that age group. In the United States, for children and adolescents ages 1 to 19, firearm-related injuries have held the top spot since 2020. For infants under 1 year old in the U.S., birth defects are the leading cause.
These numbers reflect very different realities. In lower-income countries, infectious diseases and complications around birth drive most childhood deaths. In wealthier nations, where those threats are largely controlled, injuries and violence dominate. Here’s what the data shows across each group.
Global Deaths in Children Under 5
Roughly 4.6 million children under 5 die each year worldwide, and the three biggest killers account for more than 40% of those deaths: prematurity (18%), pneumonia (13%), and birth asphyxia or trauma during delivery (10%). Infectious diseases, particularly pneumonia, diarrhea, and malaria, remain major threats for children between 1 month and 5 years old. For newborns in the first 28 days of life, the picture is different. Prematurity, birth complications, and bloodstream infections are the primary dangers.
Pneumonia alone kills over 700,000 children under 5 every year, roughly 2,000 per day, making it the deadliest single infectious disease for young children. Still, progress has been real. Deaths from pneumonia have dropped 54% since 2000, and deaths from diarrhea have fallen even further, declining 63% over the same period. Diarrheal deaths are now almost half the number caused by pneumonia. Expanded vaccination, better nutrition, access to oral rehydration therapy, and improved sanitation have all contributed to that decline.
Infants Under 1 Year in the U.S.
For American infants, the leading causes of death in 2022 were:
- Birth defects (congenital anomalies like heart defects and neural tube defects)
- Preterm birth and low birth weight
- Sudden infant death syndrome (SIDS)
- Unintentional injuries (including car crashes)
- Maternal pregnancy complications
Many of these are partially preventable. Taking folic acid before and during pregnancy reduces the risk of neural tube defects. Early and regular prenatal care improves outcomes for both mother and baby. For preterm infants, medical advances like ventilators and lung-maturing steroids have dramatically improved survival. Newborn screening programs, which test for conditions invisible at birth but dangerous if untreated, have saved countless lives over the past 50 years by catching problems early enough to intervene.
SIDS risk drops significantly with safe sleep practices. Placing a baby on their back to sleep and keeping the sleep area free of soft objects, loose bedding, toys, and crib bumpers are the most effective steps.
Children and Teens Ages 1 to 19 in the U.S.
Firearm-related injuries became the leading cause of death for Americans ages 1 to 19 in 2020, overtaking motor vehicle crashes, which had held the top position for decades. The shift was sudden. From 2019 to 2020, the rate of firearm deaths among children and adolescents jumped 29.5%, more than double the increase seen in the general population over the same period.
Firearms now account for nearly a third of all deaths among 15- to 17-year-olds. The toll is not evenly distributed. Black male teens and young adults ages 15 to 34 made up just 2% of the total U.S. population in 2022 but accounted for 34% of all gun homicides. Over half of all deaths among Black teens ages 15 to 17 were caused by guns. The gun homicide rate among Black female teens and young adults was nine times higher than among their white counterparts.
Drug overdose and poisoning also surged, increasing 83.6% from 2019 to 2020 among children and adolescents and becoming the third leading cause of death in that age group.
Older Teens Ages 15 to 19
For older adolescents specifically, the CDC reported 11,406 deaths among 15- to 19-year-olds in 2024, a rate of 51.0 per 100,000. The three leading causes were accidents (unintentional injuries), homicide, and suicide. This pattern reflects the reality that once children survive early childhood illnesses and birth-related risks, the primary threats shift from biology to environment: car crashes, violence, and mental health crises.
Why the Causes Vary So Widely
The gap between global and U.S. data tells a story about infrastructure. In countries with strong healthcare systems, clean water, and widespread vaccination, the infectious diseases that kill hundreds of thousands of young children worldwide are rare. Pneumonia and diarrhea, which together claim close to a million lives annually in children under 5, are largely treatable and preventable with resources that wealthier nations take for granted: antibiotics, oral rehydration salts, rotavirus vaccines, and access to a clinic.
In the U.S. and similar high-income countries, that success means the remaining causes of childhood death are harder to address medically. Birth defects involve complex genetics. Firearm deaths involve policy, access, and social conditions. Adolescent suicide involves mental health systems that are often overwhelmed. The leading causes of death in children, regardless of geography, reflect the specific vulnerabilities that a given society has not yet solved.