... that a pregnant woman puts out as much energy baby-building as she would if she were mountain climbing.
i've been pregnant twice and have no doubt about it!!
what i'd like to know is if "they" studied how much energy a mother releases as she chases toddlers, intervenes as referee, serves as nurse, night watch, and chef (cook just sounds too un-classy!!), acts as listener, encourager, teacher, spiritual guide and disciplinarian AND chauffeur.
with that kind of resume, i think it is quite reasonable that at the end of the day, a mother will feel like she's run a 10-km marathon AFTER scaling the aforementioned mountain!!