(September 2007) We entered the 20th century with a population of 1.6 billion people. We entered the 21st century with 6.1 billion people. And in 2007, world population is 6.6 billion.

The increase in the size of the human population in the last half-century is unprecedented.

And nearly all of the growth is occurring in the less developed countries. Currently, 80 million people are being added every year in less developed countries, compared with about 1.6 million in more developed countries. While the less developed countries will keep growing, the more developed countries may grow slowly or not at all.

Population change is linked to economic development, education, the environment, the status of women, epidemics and other health threats, and access to family planning information and services. All of these factors interact with every facet of our lives, regardless of where we live.

It is remarkable that, despite many new developments over the past 50 years, one fact looks very much the same: Populations are growing most rapidly where such growth can be afforded the least.