I'm sure you weren't suggesting that us stay at home moms don't work as hard as our go out and work hubbies :-)
I knew that I would get a post like this right after I pressed "post" on that last one :-)
No, moms ( or "Mums" as our British and Australian friends are called) have the most important and essential job on earth, and it is of course very hard at times. I would suggest, however, that it's a different and more "natural" sort of work....much more "natural" and therefore healthy for a human being than, say, working on an automobile assembly line, being an accountant, a contruction worker or most other things that people have to do away from home that is devoid of any form of nurturing environment.
I am getting on thin ice here because I haven't read studies pertaining to this specifically, but I simply have a gut feeling that doing an awful job that you absolutely hate day in and day out is more stressful on any human being than a physiologically natural activity such as raising a family, even though raising a family is far more important than anything else on Earth and is often quite stressful....it simply seems logical to me.
I have, however, read numerous studies showing the relationships between a declining womens' lifespan over the past few decades and the degree to which women have become integrated in the labor force...there's quite a tight correlation.
If a woman working for a city garbage collection company out on a smelly truck in the rain all day has the same projected lifespan as a stay-at-home mom, I would be very interested in seeing that data.