The United Nations says the world's population is expected to reach seven billion in a few days.
In a special report, the UN warns the world faces stark choices.
The BBC reports the report calls for a change of focus, no longer asking "Are we too many?" but concentrating instead on making the world better.
It identifies many reasons to celebrate, including increased life expectancy and falling fertility rates. But it also acknowledges the risks of rapid population growth.
The UN estimates that the world's seven billionth person will be born on 31 October. By the end of this century, it says the world's total population could be more than 10 billion.
The report, State of World Population 2011, says this is not a time of crisis but a moment for action.
World population milestones
1 billion - 1804
2 billion - 1927
3 billion - 1959
4 billion - 1974
5 billion - 1987
6 billion - 1999
7 billion - 2011