The answer depends on the child’s age and where they live. Globally, for children under 5, infectious diseases like pneumonia and diarrhea are the biggest killers, claiming about 1.17 million young lives each year. In the United States, firearms have been the leading cause of death for children and teens since 2020, with gun death rates in that age group rising 106 percent since 2013.
Children Under 5: A Global Picture
For the youngest children worldwide, the threats are overwhelmingly medical. Six causes account for roughly 73 percent of all deaths in children under 5: pneumonia, diarrhea, malaria, newborn infections, preterm birth complications, and oxygen deprivation at birth. Pneumonia alone is responsible for about 19 percent of these deaths, with diarrhea close behind at 18 percent.
Together, pneumonia and diarrhea kill approximately 1.17 million children under 5 every year, making up about 23 percent of all deaths in that age group. These are largely preventable with vaccines, clean water, basic sanitation, and access to antibiotics. Yet more than 70 percent of these deaths are concentrated in just 15 countries, with Nigeria (305,000 deaths), India (119,000), and the Democratic Republic of the Congo (73,000) bearing the heaviest burden.
Complications from being born too early and problems during delivery are also major killers in the newborn period. The WHO lists preterm birth complications, pneumonia, birth asphyxia, diarrhea, and malaria as the top causes of death for children under 5 worldwide.
Ages 1 to 4: Drowning Is a Hidden Risk
Within this age group, drowning stands out as a cause that many parents don’t expect. More children ages 1 to 4 die from drowning than from any other cause of death in the United States. For children ages 5 to 14, drowning is the second leading cause of unintentional injury death. Most of these incidents happen in home swimming pools, and they can occur in just minutes, often silently.
Ages 5 to 19: Injuries Take Over
As children grow older, the pattern shifts dramatically. Infectious diseases become less dominant, and injuries rise to the top. Globally in 2019, the leading causes of death for children and teens ages 5 to 19 were road traffic injuries (about 116,000 deaths), cancer (95,000), malaria (82,000), drowning (77,000), and diarrhea (73,000).
The specific risks also shift by age and sex in striking ways. For children ages 5 to 9, diarrhea remains the single biggest killer worldwide. For 10- to 14-year-olds, malaria takes the top spot. Among older teens aged 15 to 19, the picture splits sharply: road traffic injuries are the leading cause of death for males (about 49,000 deaths), while self-harm is the leading cause for females (about 33,000 deaths).
The United States: Firearms Since 2020
In the U.S., the leading causes of death for adolescents ages 15 to 19 are accidents (unintentional injuries), homicide, and suicide. But when researchers look across all children and teens ages 1 to 19, a single category has dominated since 2020: firearm-related injuries. This includes homicides, suicides, and accidental shootings.
Gun deaths among American children and teens have more than doubled since 2013. Before 2020, motor vehicle crashes had long held the top position. The shift reflects both a rise in gun violence and, to some degree, progress in reducing traffic deaths through car seat laws, graduated licensing programs, and vehicle safety improvements. The U.S. is an outlier among wealthy nations in this regard, driven largely by the widespread availability of firearms.
Where a Child Lives Changes Everything
Geography is one of the strongest predictors of whether a child survives to adulthood. A child born in sub-Saharan Africa is more than 14 times more likely to die before age 5 than a child born in Europe or North America. In high-income countries, the most common causes of childhood death are injuries, cancer, and congenital conditions. In low-income countries, preventable infectious diseases still dominate.
The gap has narrowed over the past three decades. The global under-5 mortality rate dropped 59 percent between 1990 and 2019, falling from about 93 deaths per 1,000 live births to roughly 38. Every region of the world saw improvement. But the gains have been uneven. Countries like Nigeria and Somalia still lose more than 30 children per 1,000 live births to pneumonia and diarrhea alone, while most high-income nations have driven those numbers close to zero through routine vaccination, oral rehydration therapy, and clean water infrastructure.
The practical takeaway: for young children globally, the biggest threats are treatable infections. For older children and teens, injuries, violence, and self-harm take the lead. And in the United States specifically, firearms now kill more children and adolescents than any other single cause.