The twinning rate has increased dramatically over the last four decades in developed countries. Two main factors drive this increase: delayed childbearing, as older women tend to have twins more frequently, and the expansion of assisted reproductive technology (ART), which carries an increased...

Inequality in the distribution of adult length of life - defined as age at death in the population aged 15 and over - is studied for virtually all countries of the world using a new database with over 9000 life tables covering a period of up to two centuries. The data reveal huge variation among...