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.
Macau
The growth of population in Macau mainly relies on immigrants from mainland China and the influx of overseas workers since its birth rate is one of the lowest in the world. According to "The World Factbook", Macau has the fourth highest life expectancy in the world, while its infant mortality rate ranks among the lowest in the world.