The range of numbers in the size picklist is taken from a Russian size table for men's clothing. The 'size' is actually the range from min to max of 'chest circumference' and 'height'.
We intend to change the size list in the future, because we can't create size tables for anything but men's clothing. But for now we are working on some other pressing issues.
Would you be willing to donate towards issues like these? More donations mean fixes will happen faster.
You could donate via Paypal on our website at http://valentina-project.org