Abidjan - Two million children under five die each year in central and western Africa, accounting for almost a third of all deaths worldwide in that age range, the UN children's agency said Sunday.
Progress in reducing child mortality has not affected the overall number of deaths because of "enormous" population growth, said Manuel Fontaine, Unicef's director for the region.
"Things are gradually improving. On some measures, the mortality rate for children is falling," he told AFP.
But because of population growth, "the number of children under five who die every year from preventable causes remains unchanged" at two million, he said.
That accounts for 30 percent of global deaths in that age group, even though only one in 10 of the world's under-fives are born in the region.
Underscoring Unicef's concern about the booming population growth in central and western Africa, Fontaine pointed to Nigeria, currently home to 170 million people.
The population of Africa's economic powerhouse is expected to reach up to 450 million by 2050 and close to a billion by the end of the century to become the third most populous nation on the planet.
According to projections, one birth in three will occur in Africa by 2050, and by 2100 it will become one in two, Fontaine said.
It will be impossible, he said, for central and western Africa to take advantage of a "demographic dividend" in the same way as parts of Asia, which have achieved rapid economic growth thanks to huge workforces.
"They continue to have more and more children in a population that is already very young," undermining any potential economic advantage, he said.
Fontaine noted that Ghana and Senegal, two stable democracies, have kept their populations under control compared with troubled countries such as Democratic Republic of Congo, Niger, Sierra Leone or the Central African Republic.
He said the answer must lie in improved education on health and family planning, particularly for girls.