Fairs fair
Work out the weight capacity of the plane and divide this by the customers it can carry. If a bigger person needs two seats then they can pay twice the fare. Im thinking along the lines of a benchmark weight taken from an average with anything exceeding this being paid for. If your larger but carrying very little baggage this could be taken into consideration when working out your fare.
There is the issue of too little space aswell. I dont want a huge person sitting next to me taking up what little space i have been allocated, which does end up happening. I dont care if your overweight but why should i have to suffer through a flight with your bulk overflowing into my seat? I paid good money for my seat like everyone else.
Maybe larger seats could be allocated for larger people? Obviously this would incure a larger fee though.
As for pregnent women, they made a conscious choice to have a child, the rest of us shouldnt have to pay for it.
I have no animosity towards larger people, theres plenty of people in my family that are overweight. Fairs fair though.
Cheers
Jordan