Are Baby Kicks Harmful? What Does It Feel Like to Your Fetus?

Question
 Some people vigorously shake their bellys with their hands just to get the baby to kick.  I am wondering if it is harmful in any way to the baby?  What does this feel like to the baby?

Answer
This probably doesn't feel much different to the baby than if the mother were running or jumping.  The baby is surrounded by a water-filled cushion, and this cushion is very, very good at absorbing impact and vibration from the outside.  If you really want to encourage the baby to kick, though, a better method would be to drink some orange juice and lie down for a while.  Babies are lulled to sleep by motion and tend to wake up when mom is still.