Shaving is not about mere hygiene or men would be the ones to shave their bodies. They make more hair generally and have a stronger smell. Not buying the hygiene argument!
My ex shaved "down under" to keep it cooler (he was a chef and it got HOT). Male bikers and swimmers shave to be more aerodynamic.
When I was pregnant, I lost all my leg hair. I don't know if it's a normal occurrence with pregnant women, but if so, it could toss out the shaved legs=childlike theory.
After all, there are a lot of secondary traits related to pregnancy that men (and women) like (ex- big boobs, full thick hair, etc...). The first "sex symbol" (the Venus of Willendorf) is a pregnant woman.