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.
Sex education
A sex survey by the World Health Organization concerning the habits of European teenagers in 2006 revealed that German teenagers care about contraception. The birth rate among 15- to 19-year-olds was very low—only 11.7 per 1000 people, compared to 27.8 births per 1,000 people in the UK, and 39.0 births per 1,000 people in Bulgaria (which, incidentally, has the highest birth rate in Europe).