I hope
Saige is right about some standard based on
real people coming into use, because at least here in the
U.S.,
women's clothing is proportioned for
Barbie dolls, not realistic figures.
Myself as an example: I don't have a particularly unusual figure. My hips are bigger around than my bust, but my waist is smaller than either. I noticed when looking at the size chart in the Frederick's of Hollywood mail catalog that my bust size fell into the range of "small" for their sizing, my hips into "medium", and my waist into "large." 'Hey,' I thought, 'that explains why I can never find a teddy from any manufacturer that will fit over my hips without being way too loose in the chest.'
You might think Frederick's would be a special case, oriented toward women with the figures our society likes best. Well, recently I was ordering some jeans from a catalog called Newport News, which seems to have ordinary, everyday clothing for women. My mother and grandmother get this catalog. And again, by their sizing chart, my bust is small (size 6), my hips are medium (size 10) and my waist is large (size 14). The table of measurements and sizes takes up about a quarter of the page; the rest is full of advice on how to figure out which measurement to pay most attention to for each type of garment. (Unfortunately, when you shop in a store you aren't supplied with such a helpful table for each brand the store carries.) And this isn't even considering height (I fall at the tall end of the petite range), just girth!