According to an article that was released on Dec 13, 2007 by Live Science, the answer is simple…. Like cushy baby strollers, women’s bodies have evolved spines that are more flexible and supportive to keep from tipping over while walking during pregnancy.
Pregnancy brings loats of hormonal changes as it transforms a woman’s body into a baby incubator. As the baby grows, so does a woman’s belly. No surprise, the front cargo pulls her center of gravity off kilter.
If the body architecture failed to take counter measures, pregnant women all over the world would be tipping over left and right. Oh my.
According to researcher, Katherine Whitcome, an anthropologist at Harvard University found that due to natutral selection that occured over two million years ago, women’s spines evolved during pregnancy to in order to handle the new weight.
Whitcome and group studied 19 pregnant women between the ages of 20 and 40 from their first trimester until after they gave birth. They found that when the mass of the developing baby reached about 40 percent of its full-term weight, the mother’s posture began to change.
They found three things in this study:
1) Pregnant women leaned back as the position of their center of mass was changing.
2) Compared with male spines, the curvature of the spine in the lower back extended across three vertebrae in women compared to only two vertebrae for males. By loading the weight across three vertebrae, this helps the expectant mother to re-alignher center of gravity above her hips and offset the destabilizing weight of the baby.
3) The female vertebral joints are relatively larger and extend more down the spine than those of males. The extra support helps to offset strain on the spine that occurs when a pregnant woman leans back to balance the weight of the fetus
The enhanced curvature and reinforcement of the lower spine are key to maintaining normal activities during pregnancy.
To read more about this article and other articles from Live Science, click here.