The science is in: "the upper limit of energy that human bodies can expend consistently over time is one pushed by endurance athletes... and people who are pregnant and lactating." (published, Science Advances)
The study was done by a group of anthropologiests, evolutionary biologiests, and public health researchers from around the world. The group charted the metabolic rates of runners who competed in Race Across the USA, a 14-week race spanning more than 3,000 miles. Competitors of this race cover roughly a marathon per day, size days a week.
Results showed that the metabolic rates in these ultra-long distance runners slowed to nearly the same rate of pregnant women.
When the body is subjected to extreme activity for an extended period of time, after a point, it will adapt, and one of the most extreme things a human body can go through is, apparently, running a 3,000 mile race -- or being pregnant.
Imagine what this says about the condition and strength of the pregnant endurance athlete. Consider world champion athlete Alysia Montano, who ran the 800m in the US Track and Field Championships when she was 7 weeks from her delivery date. Montano completed the race in 2 minutes, 31.13 seconds – just 35 seconds slower than her personal best in 2010.
So while there's nothing unusual about seeing a pregnant women amongst us, it is unusual for her to be recognized for the herculean feat she is accomplishing every second of her routine day.
Thanks to the scholars and scientists who let it be known!