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.
Human sex ratio
Another hypothesis has been inspired by the recent and persistent high birth sex ratios observed in Georgia and Armenia—both predominantly Orthodox Christian societies—and Azerbaijan, a predominantly Muslim society. Since their independence from Soviet Union, the birth sex ratio in these Caucasus countries has risen sharply to between 1.11 and 1.20, some of world's highest. Mesle et al. consider the hypothesis that the high birth sex ratio may be because of the social trend of more than two children per family, and birth order possibly affects the sex ratio in this region of the world. They also consider the hypothesis that sons are preferred in these countries of the Caucasus, the spread of scans and there being a practice of sex-selective abortion; however, the scientists admit that they do not have definitive proof that sex-selective abortion is actually happening or that there are no natural reasons for the persistently high birth sex ratios.