Birth rate
As of 2017, Niger has the highest birth rate in the world with 49.443 per thousand people. 
Japan has one of the lowest birth rates in the world with 8 per thousand people.
While in Japan there are 126 million people and in Niger 21 million, both countries had around 1 million babies born in 2016.
Sardinia
It is the region with the lowest total fertility rate (1.087 births per woman) and the second-lowest birth rate of Italy (which is already one of the lowest in the world). Combined with the aging of population going rather fast (in 2009, people older than 65 were 18,7%), rural depopulation is quite a big issue: between 1991 and 2001, 71,4% of Sardinian villages have lost population (32 more than 20% and 115 between 10% and 20%), with over 30 of them being at risk to become ghost towns. Nonetheless, the overall population has been increasing because of a considerable immigration flow, mainly from the Italian mainland, Eastern Europe (esp. Romania), Africa and Asia.
Average life expectancy is slightly over 82 years (85 for women and 79.7 for men). Sardinia shares with the Japanese island of Okinawa the highest rate of centenarians in the world (22 centenarians/100,000 inhabitants).
Sardinia is the first discovered Blue Zone, a demographic and/or geographic area in the world with an oversize concentration of centenarians and supercentenarians.