This is the first time that I've had up close interaction with a pregnant cat. It fascinates me to leave my hand on her belly for a while and feel for the movement of the kittens. If we can both sit quietly for long enough (Tabitha is more likely to wiggle than I am), I can feel tiny little feet kicking and bumping.
On very rare occasions, like just now, when Tabitha lies on my desk, I can actually see tiny movements in her belly, not caused by her own breathing or heart beat.
I'm actually a little surprised that one does not feel or see more movement from four kittens. Of course, kittens, like other mammals (other than humans and great apes) are born at an earlier stage of development, and do more developing outside the womb. For example, humans are born with their eyes open, looking at everything (except when we scrunch them closed to cry), whereas kittens don't even open their eyes for two weeks.