The global population will hit 7 billion on Oct. 31, according to a projection by researchers at the United Nations.

The world's population reached 1 billion in 1800 and 2 billion in 1925 according to UN data reported in the journal Science. The world's population has grown spectacularly since the industrial periods of the mid-18th century.

By 2050, the population will hit 9.3 billion, and 97 percent of the growth will come from less developed regions said David Bloom, the author of the study and economist at Harvard University.

However, the growth rate is expected to slow down by the year 2100 as the countries with the highest birth rates develop better female education and family-planning systems. Sex education and access to contraceptives may be a game changer, especially in regions like Africa where the youth population is high.

Currently, In Japan, China and Europe, women are having fewer than two babies, while in less developed countries the average is around five.

People try to board a crowded passenger train to take part in the Nat, or spirits, festival, at Taungbyone station
People try to board a crowded passenger train to take part in the Nat, or spirits, festival, at Taungbyone station, near Mandalay August 21, 2010. The festival is popular with young people for merrymaking and drinking. Spirit mediums take part in the festival and people of all ages can join in the Nat dance. Reuters
Laundry hangs outside a student dormitory at a college in Wuhan
Laundry hangs outside a student dormitory at a college in Wuhan, Hubei province March 5, 2009. Picture taken March 5, 2009. Reuters
A view of a building at the beach of Torremolinos near Malaga
A view of a building at the beach of Torremolinos, near Malaga, March 27, 2009. Reuters
A view of a residential building in Shanghai June 10, 2009.
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Roman Catholic pilgrims press together while following the image of the local saint Our Lady of Nazareth
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People try to board a crowded passenger train to take part in the Nat, or spirits, festival, at Taungbyone station
People try to board a crowded passenger train to take part in the Nat, or spirits, festival, at Taungbyone station, near Mandalay August 21, 2010. The festival is popular with young people for merrymaking and drinking. Spirit mediums take part in the festival and people of all ages can join in the Nat dance. Reuters
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