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.