The United States ranks third behind China and India with 320 million people, followed by Indonesia at 250 million and Brazil at 200 Million. Nigeria ranks seventh at 174 million, just behind sixth ranking Pakistan at 182 million. By 2050, the report said, Nigeria will rank third at 440 million, compared to the United States estimated 401 million people.

Fertility, mortality and migration rates will affect future population trend trajectories, especially fertility, Wilmoth said in a statement accompanying the 50-page report. "For the world as a whole, fertility has fallen rapidly in recent decades, especially since the 1960s," he said. "Several large developing countries, including China, India, Indonesia, Iran, Brazil, South Africa and many others have experienced a rapid fall in the average number of children per woman," he said. "This has led to a reduction in population growth rates in much of the developing world."

"At the same time, many countries of Europe, East Asia and elsewhere, now have very low levels of fertility, well below their 'replacement level' of around 2.1 children per woman," Wilmoth said.

Most of the countries with relatively high levels of fertility are on the UN's list of 49 least developed countries, with many in sub-Sahara Africa.

Related

• Vietnam's population reaches over 88.5 mln
• Japan's population declines by record 0.22 pct in 2012
• Shanghai reports 6.7% rise in expat population
• NYC population hits all-time high

Go to Forum >>0 Comment(s)