yes, when i attended the pre-natal class in the hospital. the nurse taught us to do this exercise during pregnancy. They explained it's very very important to strengthen up the muscle because we 'never' do exercise there.
In our mother's generation, since the education is not popular, many mother didn't know they need to do this exercise before and after giving birth to bb. therefore, when they grows older, the muscle is so lose and lack elasticity that sometimes the pp can't hold. When they have some pp inside the kidney, and them sneeze, or run, or even laugh very strongly... few drops of pp will come out because the muscle is not strong enough to hold it.