It is a familiar scene in movies and on TV shows; immediately after a baby is delivered, the doctor holds it by the legs and gives it a firm rap on the butt and crying ensues. However, in reality, crying is actually induced by simply stroking and massaging the baby's skin. But why make the baby cry at all? Isn't just being born harrowing enough? Well, as it turns out, doctors have a very good reason to make a baby cry.