Birth rate
According to the CIA's "The World Factbook", the country with the highest birth rate is Niger at 6.49 children born per woman and the country with the lowest birth rate is Taiwan, at 1.13 children born per woman.
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.