Modern standard sizes for women’s clothing first began in the 1940s in the U.S. However, women preferred smaller sizes, so over the course of the next several decades, the fashion industry began downsizing its sizes, so that a 16 in the 1940s was a 12 in the 1960s and a 6 in recent times.
Thanks to this downsizing there is also a large discrepancy between American and European sizes – an American size 10 is equivalent to a British 14.