Nearly 2.5 million people were surveyed in Bangladesh, China, the Philippines, Thailand and Vietnam by UNICEF and the Alliance for Safe Children, a U.S.-based aid group. The survey found injuries were the leading cause of death in children older than one year.
Drowning was the top cause of injury-related deaths in all countries, accounting for about half of all cases.
But the report said drowning was largely missing from child mortality statistics because many children who drown are often never taken to hospitals.
"You have this child floating face-down in a pond, and you don't take it to a hospital," said Dr. Michael Linnan, a co-author and technical director of the Alliance for Safe Children. "So that death never shows up."
The Asia-Pacific region is home to vast coasts and waterways, yet many people cannot swim. Thousands drown every year during powerful typhoons, monsoon floods or simply from falling into rivers or ponds. Linnan estimated about 240,000 children up to 17 years old drown each year across the region.
He said governments should raise community awareness about the need to better supervise small children around water and teach them how to swim. He said the Alliance for Safe Children was involved in a program in Bangladesh that has taught 23,000 children to swim and there were plans to duplicate it nationally.
"It's like immunizations," Linnan said. "You provide them with this lifelong protective ability."
Child mortality from infectious diseases in developing Asian countries has dropped sharply in recent years, thanks to greater access to vaccines along with work to decrease diarrhea and respiratory diseases. Improvements in nutrition have also helped.
Babies are still at the highest risk of dying during their first month of life, and disease poses the biggest threat during their first year. But injuries are the biggest danger from then on.
Boys are more at risk of being killed by injuries than girls, while children living in rural areas are more likely to die from accidents than those in cities. The survey looks at children from birth to 17 years old. Data was collected in rural and urban areas nationwide in all countries except China, where large samples were surveyed in Beijing and southern Jiangxi province.
Road accidents were the second-biggest killer of children in the countries surveyed, where traffic is typically congested and chaotic and laws are often ignored. The highest number of traffic deaths occur in the teen years.
"Road traffic is a major, major issue in countries like Vietnam, Laos and Cambodia," said Hisashi Ogawa, regional adviser for healthy settings and environment at the World Health Organization's Western Pacific office. "It's not just kids on bikes, but also kids on the streets," said Ogawa, who was not involved in the study.
Ogawa said much emphasis has recently been directed at Vietnam, where motorbikes are the primary mode of transportation. A helmet law went into effect in December, but a loophole exists exempting children and their parents from fines for riding without helmets.