I know this is going to sound a little weird but stick with me here. Overweight and obese people and pregnant women have several similar mobility/postural difficulties, and also suffer some musculo-skeletal problems due to carrying lots of excess weight. They might easily tire after standing for longer periods of time, have trouble fitting into smaller spaces, have some digestive problems (heartburn, constipation), not be able to walk for long periods of time, have lots of lower back pain, etc.
However, I think people in general are much more generous and accommodating of pregnant women’s special needs than those of the obese. There are special “pregnant women” parking spots that are closer to the store entrance, without a counterpart for obese people (although I suppose if you are overweight enough for it to qualify as a handicap, then you also get to park close). People will jump up to give a pregnant woman a seat on a bus or in a crowded room, and no one does that for the overweight. I’m sure we could find more examples.
So why do we treat the two groups of people with similar problems so differently? My first thought is that because overall, pregnant women are serving a function that everyone benefits from, i.e. producing children, which are generally necessary for today’s middle-aged and young people to live a life of leisure once they get older (taking over their jobs, paying social security, etc). No one really benefits from obese people being overweight, except maybe the junk food industries. However, there is usually as least as much, if not more, intention involved in getting pregnant as opposed to becoming obese; most obese people do not set out to become that way, it just happens due to a variety of factors, one being decreased vigilance or control of calories in versus calories out. Many pregnant women planned to become that way, and the majority of others had a problem with their birth control method that was probably user-generated. Also, most pregnant women don’t have children because of their obligation to populate the world for future generations, but for more self-centered reasons, because they simply want a child. And finally, overpopulation is a significant problem in many countries, so by having children pregnant women might be doing the world a net negative, if that makes sense.
So why the difference in attitude towards these groups? I feel like it should be obvious, but I can’t really think of it . . . it seems more of a gut feeling that pregnancy is neutral to good, whereas obesity is bad, and shouldn’t be encouraged. But that’s all I can come up with. And even the most staunch zero-growthers would still not look up pregnant women with the same disdain that many people use for the obese, would they?