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.
Woman
The total fertility rate (TFR) – the average number of children born to a woman over her lifetime — differs significantly between different regions of the world. In 2016, the highest estimated TFR was in Niger (6.62 children born per woman) and the lowest in Singapore (0.82 children/woman). While most Sub-Saharan African countries have a high TFR, which creates problems due to lack of resources and contributes to overpopulation, most Western countries currently experience a sub replacement fertility rate which may lead to population ageing and population decline.