The US Business Insider published a paper devoted to ten countries with serious demographic problems.

A special place in the material is also dedicated to the demographic crisis in Bulgaria.

The population of Bulgaria, the European Union's poorest member, may soon become as low as it was in the aftermath of World War II, Bloomberg reported.

Bulgaria's population is shrinking faster than any other country in the world; it is expected to hit only 5.4 million in 2050, down from 7 million last year, according to Quartz.

In addition, the country has seen an increase in emigration as citizens seek job opportunities elsewhere. Bulgaria's fertility rate is only 1.46 children per woman.

"The decline in the active population is a social and economic bomb that will explode unless we take adequate measures," Bulgaria's deputy labor minister, Sultanka Petrova, told Bloomberg last year.

Surprisingly, however, major demographic problems are present in some of the most populated countries in the world. Problems with low birth could be problematic for United States, Japan, South Korea, Spain, Italy, the United Kingdom. Most of these countries, however, managed to compensate for the decline in birth rates with immigrant admissions.