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.
Demographics of France
The immigration rate is currently lower than in other European countries such as United Kingdom and Spain; however, some say it is unlikely that the policies in themselves account for such a change. Again, as in the 1920s and 1930s, France stands in contrast with the rest of Europe. Back in the 1920s and 1930s, when other European countries had a high fertility rate, France had a low fertility rate and opened its doors to immigration to avoid a population decline. Today, it is the rest of Europe that has very low fertility rates, and countries like Germany or Spain avoid population decline only through immigration. In France, however, the fertility rate is still fairly high for European standards. It is, in fact, the highest in Europe after Ireland (the EU) and Albania (perhaps higher than Ireland's) and so most population growth is due to natural increase, unlike in the other European countries.