There are several reasons that have caused population explosion:

• Development in various field have improved the quality of life significantly in the last century. Especially, increased health facilities such as vaccination and better living conditions has lead to population explosion.

• Decreased in maternal mortality rate and infant mortality rate and increase in the number of people in reproducible age have lead to increased population.

• The death rate has decreased and birth rate has increased in past 50 years due to better health facilities, food supply and other advancements