The growth rate of the world population has slowed down, according to the US Census Bureau.
Africa's population is set to fall
Its report says there were 74 million more people in 2002 - well below the 87 million added in 1989-90.
The rate of growth peaked 40 years ago, when it stood at about 2.2% a year. The bureau partly attributes the drop to women having fewer children.
It also projects a population decline in Africa because of the lower life expectancy due to HIV-Aids.
In 1990 women around the world gave birth to 3.3 children on average, the report says.
By 2002, the average had dropped to 2.6 children - slightly above the level needed to assure replacement of the population.
The bureau's projections show the level of fertility for the world as a whole descending below replacement level by 2050.
It forecasts there will be nearly 9.1bn people by 2050, just under a 50% increase from the 6.2bn in 2002.
The report suggests that the proportion of people over the age of 65 will continue to increase - from 7% to 17% by 2050.
The projections also indicate that by 2010, some African countries will experience falls in life expectancy at birth to about 30 years - a level not seen since the early 20th Century.
Much of this trend is likely to result from Aids, the report says.
It adds the trend could reverse if Aids education programmes are expanded in developing nations.
It points to positive signs in Thailand, Senegal and Uganda, where the epidemic appears to have been stemmed.