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.
Sterilization (medicine)
In countries with high population rates, such as China and India, compulsory sterilization policies or incentivizes to sterilization may be implemented in order to lower birth rates. While both countries are experiencing a decline in birth rate, there is worry that the rate was lowered too much and that there will not be enough people to fill the labor force. There is also the problem of son-preference: with greater sex selection technology, parents can abort a pregnancy if they know it is a female child. This leads to an uneven sex ratio, which can have negative implications down the line. However, experiencing a lower population rate is often very beneficial to countries. It can lead to lower levels of poverty and unemployment.