The global childhood mortality rate has halved in the past two decades, according to Unicef and the World Bank.
The UN children's fund said in a report that the number of infants and children aged 5 and under who died before reaching the age of five had dropped from 12 million in 1990 to 6.9 million in 2011.
The report released Wednesday credited improvements in nutrition, access to vaccines and treatments, better care of infants post natally and the use of insecticide-treated mosquito nets, the Associated Press reported.
A long-term strategy to improve girls' education was also paying dividends.
The lowest child mortality rate in 2011 was in Singapore, which had 2.6 deaths of children under age 5 per 1,000 live births, while the rate in the United States was eight per 1,000 births, the report said.
Globally the rate was 51 deaths per 1,000 births.
However, the report said, South Asia and Africa had not kept pace with the rest of the world, and the country-to-country variation in child mortality rates was huge and growing.
About half of all child deaths occur in five countries: India, Nigeria, the Democratic Republic of the Congo, Pakistan and China.
And, Agence France-Presse quoted executive director Anthony Lake as saying, "Any satisfaction at these gains is tempered by the unfinished business that remains."
About 19,000 children were still dying each day from largely preventable diseases, with pneumonia the biggest killer — causing about a fifth of all under-5 deaths worldwide, 1.3 million in total, according to Australia's Fairfax media.
Children were most at risk in their first month of life: 40 percent of recorded deaths occurred in that that stage of life.