Women’s Bodies Have Evolved Spines
Anthropologists discovered that women's bodies have evolved spines which keeps us upright and hinders us from tipping over when we're pregnant. With the dramatic changes that women's bodies go through during pregnancy, the body accommodate these changes which helps us to keep normal activities during pregnancy, hence reduces the pressure on the spine.
Findings shows that women's spine evolved atleast 2 million years ago when people started walking upright.
They also studied pregnant women and found that women "extend their upper body at the lower back" as the "the position of their center of mass was changing." Further,
The researchers also examined participants' spines and compared results with male spines. In both women and men, the curvature of the spine in the lower back, called the lordosis, stabilizes the upper body above the lower body. While male lordosis curves across just two vertebrae, the curvature extends across three vertebrae in women, Whitcome said.
Another study that shows just how special we women are 
via Live Science
April 22nd, 2010 at 3:49 pm
The human body is an extraordinarily built machine, it got it all figured out way ahead. Well this would explain why most women don’t have spine problems after pregnancy. Isn’t that amazing?