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.
Mid-twentieth century baby boom
Many European countries, Australia and New Zealand also experienced a baby boom. In some cases the total fertility rate almost doubled. The American birth model, conceived by demographer Frank Notestein, was punctuated by an end to the upsurge in births and a return to pre-war levels. In many European countries the first year of the Post World War II baby boom was the year 1946, but in Germany the first year was the year 1955 in Finland the largest birth rate was in August and September 1945. Japan had two separate baby booms. The first started in 1947, the second in 1971. Prior to World War II, mortality rates in Europe and America were on a general decline due to improved nutrition and medicine, and a surge in births were previously not experienced at such a large scale. Based on this model, baby boom years for other countries regarded for having a baby boom are as follows: