Birth rate
The region of Sub-Saharan Africa has the highest birth rate in the world. As of 2016, Niger, Mali, Uganda, Zambia, and Burundi have the highest birth rates in the world. This is part of the fertility-income paradox, as these countries are very poor, and it may seem counter-intuitive for families there to have so many children. The inverse relationship between income and fertility has been termed a "demographic-economic "paradox"" by the notion that greater means would enable the production of more offspring as suggested by the influential Thomas Malthus.
Social issue
Germany has one of the lowest birth rates in the world. In 2012, its national fertility rate was 1.41 children per woman, up slightly from the 2002 rate (1.31), but still well below the replacement rate of 2.1 children per woman. (By contrast, the United States had a fertility rate of 2.06 in 2012). At the same time, Germans are living longer, with a life expectancy of 80.19 years (77.93 years for men and 82.58 years for women) – 2012 estimates. This demographic shift is already straining the country's social welfare structures and will produce further economic and social problems in the future.
The Mikrozensus done in 2008 revealed that the number of children a German women aged 40 to 75 had was closely linked to her educational achievement.