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.
List of countries by natural increase
The birth rates and death rates in columns one and two are the CIA World Factbook estimates for the year 2017 unless otherwise noted, rounded to the nearest tenth (except for Mayotte with 2010 estimates). The natural increase rate in column three is calculated from the rounded values of columns one and two.