A number of countries are expected to see a decline in their demographic growth with low birth rates and increasing waves of migration, threatening their population base aging and shrinking population, at a time when the global population is likely to rise in the coming decades.

In a report published by Business Insider, writer Andy Kiers said Japan faces a marked drop in demographic growth due to the reluctance of young people to have children. The BBC has revealed attempts to slow down the population decline in Bulgaria by improving educational and economic opportunities and reducing immigration to other countries.

The following are the 20 countries that are expected to experience the largest population decline between 2020 and 2050, according to the demographic forecast published by the United Nations in the next few decades.

Italia
Its population is expected to decline from 60.5 million in 2020 to 54.4 million in 2050, with a population decline of 10.1%.

Cuba
The population is expected to decline from 11.3 million in 2020 to 10.2 million by 2050, a decrease of 10.3%.

Northern Macedonia
The population of this republic is likely to decline from 2.1 million in 2020 to about 1.9 million in 2050, with a population decline of 10.9%.

Portugal
The population is expected to decline by 10.9%, from 10.2 million in 2020 to 9.1 million in 2050.

Georgia
It will see a decline from 4.0 million in 2020 to 3.5 million in 2050, a decline of 11.8%.

Poland's population to decline by 12% between 2020 and 2050 (European)

Poland
Demographic growth is likely to decline from 37.8 million in 2020 to 33.3 million in 2050, a decline of 12%.

Hungary
According to forecasts, the population will decline by 12.3% between 2020 and 2050 and decline from 9.7 to 8.5 million.

Estonia
The population is expected to decline from 1.3 million in 2020 to 1.2 million in 2050, a decrease of 12.7%.

Greece
There is a high probability that the population will fall from 10.4 to 9.0 million over the next three decades, with a decline of 4.13%.

Romania
The population of 19.2 million is projected to decline to about 16.3 million by 2050 and the decline is estimated at 15.5%.

Albania
Demographic growth is projected to decline by 15.8%, with the population returning from 2.9 million in 2020 to 2.4 million in 2050.

Japan's population to fall 16.3% in 2050 (Getty Images)

Japan
The population of 126.5 million is likely to fall to 105.8 million in 2050, which means that the population will decline by 16.3%.

Moldova
The population is expected to decline from four million in 2020 to 3.4 million in 2050, with a decline of 16.7%.

Croatia
The population is projected to decline by 18% between 2020 and 2050, and the population will decline from 4.1 to 3.4 million.

Bosnia and Herzegovina
The population is expected to decline from 3.3 million in 2020 to 2.7 million in 2050, with a population decline of 10.9%.

Serbia
According to UN projections, the population will decline from 8.7 million in 2020 to 7.1 million in 2050, a decrease of 18.9%.

Ukraine
The population is likely to decline by about 19.5%, from 43.7 million in 2020 to 35.2 million in 2050.

The expected demographic decline in Ukraine in 2050 will be 19.5% (European)

Latvia
The population is likely to decline by 21.6%, and the population will fall from 1.9 million in 2020 to 1.5 million in 2050.

Lithuania
The population is expected to decline from 2.7 million in 2020 to 2.1 million in 2050, which means that the number will decline by 22.1%.

Bulgaria
The population is projected to decline from 6.9 million in 2020 to 5.4 million in 2050, with a 22.5% decline.