Today is World Population Day. At the call of the United Nations, this day is being celebrated in different countries of the world with various programs. According to the United Nations, it took millions of years for the world's population to reach one billion, and in the following 200 years, the world's population increased seven times.

In 2011, the world's population reached seven billion, and in 2021, it will reach seven billion and 90 billion. 

The population is constantly increasing. It is estimated to reach eight billion 50 million in 2030, nine billion 70 million in 2050 and 10.9 billion in 2100. Changes in fertility rates, increasing urbanization and migration have far-reaching effects on population growth, a study has shown.

Compared to the past, the study concludes that the youth of reproductive age have reduced their desire for children in terms of financial lack, insecurity, health, education, housing and other issues. According to a survey conducted by the United Nations Population Fund with more than 14,000 people in fourteen countries, the reasons why the majority of adults of reproductive age do not have children according to their wishes are problems in child care, job insecurity, health, climate change, epidemics, war and environmental damage.