Demographics of the world
According to the CIA - The World Factbook, the country with the highest birth rate currently is Niger at 51.26 births per 1000 people. The country with the lowest birth rate is Japan at 7.64 births per 1000 people. Hong Kong, a Special Administrative Region of China, is at 7.42 births per 1000 people. As compared to the 1950s, birth rate was at 36 births per 1000 in the 1950s, birth rate has declined by 16 births per 1000 people. In July 2011, the U.S. National Institutes of Health announced that the adolescent birth rate continues to decline.
Demographic transition
Some countries have sub-replacement fertility (that is, below 2.1–2.2 children per woman). Replacement fertility is generally slightly higher than 2 (the level which replaces the two parents) both because boys are born more often than girls (about 1.05–1.1 to 1) and to compensate for deaths prior to full reproduction. Many European and East Asian countries now have higher death rates than birth rates. Population aging and population decline may eventually occur, assuming that the fertility rate does not change and sustained mass immigration does not occur.